Treatment liquid for plastic film, primer liquid for printing, ink composition, and method for ink jet

ABSTRACT

This invention provides a treatment liquid for an ink jet recording medium having a recording face of a plastic film, wherein the treatment liquid including at least a specific cyclic ester compound or a specific cyclic amide compound, a primer liquid for printing, and an ink composition. According to the present invention, a plastic recorded matter possessing excellent adhesion and waterfastness can be formed on a recording medium having a recording face of a plastic film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/093,874 filed Apr. 26, 2011 which is a divisional of application Ser.No. 11/883,414 filed Jul. 31, 2007, which is national phase of PCTApplication JP2006/306855 filed on Mar. 31, 2006, which claimed thebenefit of the following Japanese Patent Applications: 103116/2005 filedMar. 31, 2005, 103686/2005 filed Mar. 31, 2005, 103806/2005 filed Mar.31, 2005, 102713/2005 filed Mar. 31, 2005, 103733/2005 filed Mar. 31,2005, and 103767/2005 filed Mar. 31, 2005, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a treatment liquid for a plastic film.More particularly, the present invention relates to a treatment liquidcomposition to be used in the printing of a water-based ink compositionon a recording medium having a recording face formed of a plastic film,which treatment liquid composition is coated onto the recording facebefore printing of a water-based ink composition. The present inventionalso relates to a primer liquid to be used for printing for a plasticfilm. More particularly, the present invention relates to a primerliquid composition to be used in the printing of a water-based inkcomposition on a recording medium having a recording face formed of aplastic film, which primer liquid composition can be coated onto therecording face before printing of a water-based ink composition to forma primer film. Further, the present invention relates to an inkcomposition for a plastic film. More particularly, the present inventionrelates to an ink composition suitable for use for an ink jet recordingmedium having a recording face formed of a plastic film. Furthermore,the present invention relates to an ink jet recording method using theabove treatment liquid, primer liquid, or ink composition.

2. Background Art

An ink jet recording method is a printing method in which droplets of anink composition are flied to and deposited onto a recording medium inits recording face to perform printing. This method has a feature thathigh-resolution and high-quality images can be printed at a high speedwith a relatively inexpensive apparatus. Regarding recording media forink jet recording, there is an increasing demand for proper propertiesof materials constituting the recording media, for those of commonlyused papers and the like, as well as plastic films.

Plastic recorded matters produced by printing onto plastic films or thelike are expected to be used in applications for which paper cannot beused, for example, outdoor signs. Accordingly, higher waterfastness andlightfastness are required of plastic recorded matters. Also regardingprints such as labels which are touched by the hand, plastic recordedmatters are more suitable than paper printed matters. Also in this case,fastness properties such as fastness to rubbing/scratch are required ofthe recorded matters.

When ink jet recording is carried out using non-surface-treated plasticfilms for ink jet recording as an ink jet recording medium, for example,non-surface-treated polyvinyl chloride films, solvent-type inks,UV-curable inks, or two-component-type curable inks have hitherto beenused. Solvent-type inks, however, emit odor of solvents, and, in somecases, harmful components are contained in the solvent volatilecomponent. Also for UV curable inks, two-component-type curable inks andthe like, in some cases, the curable monomer used contains harmfulcomponents.

When ink jet recording is carried out using a conventional water-basedink on a non-surface-treated plastic film for ink jet recording,recorded images are unsatisfactory in adhesion, scratch resistance andwaterfastness.

Regarding the use of plastic films for ink jet recording, JapanesePatent Laid-Open Publication No. 286940/1997 proposes a method in whicha colorant or a dispersing resin as the ink component is coagulated andcured using a water-based ink.

Further, for example, Japanese Patent Laid-Open Publication No.11486/2003 discloses an ink jet recording method using a pretreatmentliquid. This recording method, however, aims to record high-quality andwaterfast images on commonly used recording media but does not aim atprinting on plastic films. Furthermore, for example, Japanese PatentLaid-Open Publication No. 114140/1998 describes that an amide-containingreaction solution is used in an ink jet recording method using twoliquids. In this reaction liquid, the amide is added from the viewpointof improving print quality and print stability, and this publicationdoes not suggest printing onto plastic films.

On the other hand, for example, Japanese Patent Laid-Open PublicationNo. 103785/2002 discloses that, in an ink composition for ink jetrecording, lactams or lactones can be used as carrier medium materials(see, for example, claim 12 and the like in this publication). Thispublication, however, describes lactams and lactones only as an exampleof solvents for dissolving a colorant in an ink composition and does notsuggest printing of the ink composition onto a recording medium having arecording face formed of a plastic film.

Further, Japanese Patent Laid-Open Publication No. 48934/2001 disclosesan ink composition containing a cyclic amide compound, and JapanesePatent Laid-Open Publication No. 96345/2003 discloses that2-pyrrolidone, caprolactam and the like are usable as wetting agents inink compositions. These publications, however, do not suggestadvantageous printing of an ink composition onto a recording mediumhaving a recording face formed of a plastic film.

Accordingly, the development of an ink jet recording method using awater-based pigment ink, which can produce plastic recorded mattershaving excellent waterfastness and rubbing resistance, has been desired.

SUMMARY OF THE INVENTION

The present inventors have now found that plastic recorded mattershaving significantly improved rubbing resistance, scratch resistance,and waterfastness can be produced by treating the surface of a plasticfilm on its recording face, that is, by previously coating a specificcyclic ester compound- or specific cyclic amide compound-containingtreatment liquid having a specific composition onto the recording face,prior to the deposition, onto the recording face, of a thermoplasticresin-containing water-based ink composition which can be brought to afilm upon heating.

The present inventors have further found that, when plastic recordedmatters are formed by depositing an ink composition, plastic recordedmatters having significantly improved rubbing resistance, scratchresistance, and waterfastness can be produced by previously coating aspecific cyclic ester compound- or specific cyclic amidecompound-containing primer liquid having a specific composition onto thesurface of a plastic film to treat the surface of the plastic film and,at the same time, to form a primer film on the plastic film, prior tothe deposition of the ink composition.

The present inventors have further found that, when ink jet recording iscarried out on a recording medium having a recording face formed of aplastic film, recorded matters having significantly improvedwaterfastness and adhesion between the recording medium and the inkcomposition can be formed by using a specific solvent-containing inkcomposition having a specific composition. Regarding the solvent used,the use of a low-volatility cyclic ester compound or cyclic amidecompound in combination with a high-volatility cyclic ether compound ismore useful for achieving the above improvement.

The present invention has been made based on such finding.

Accordingly, an object of the present invention is to provide atreatment liquid for a plastic film that, when used with a water-basedink composition containing a thermoplastic resin, can realize theformation of a plastic recorded matter possessing excellent rubbingresistance, scratch resistance, and waterfastness. Another object of thepresent invention is to provide an ink jet recording method that canform a plastic printed matter possessing excellent rubbing resistance,scratch resistance, and waterfastness using the treatment liquid and thewater-based ink composition.

Still another object of the present invention is to provide a primerliquid for printing for a plastic film that can realize the formation ofa primer film having high adhesion to an ink composition deposited toform a plastic recorded matter possessing excellent rubbing resistance,scratch resistance and waterfastness. A further object of the presentinvention is to provide an ink jet recording method using the primerliquid.

Another object of the present invention is to provide an ink compositionfor ink jet recording that can form a plastic recorded matter possessingexcellent adhesion and waterfastness on a recording medium having arecording face formed of a plastic film. Still another object of thepresent invention is to provide an ink jet recording method using theink composition.

According to one aspect of the present invention, there is provided atreatment liquid for an ink jet recording medium having a recording faceformed of a plastic film, wherein said treatment liquid comprising atleast

a heterocyclic ketone compound selected from the group consisting ofcyclic ester compounds of formula (1), cyclic amide compound of formula(2), and a combination thereof, and

a main solvent:

-   -   wherein        -   R¹ represents a straight chain or branched chain C2 to C12            saturated hydrocarbon chain, and        -   X¹ represents —CH₂— or —O—; and

-   -   wherein        -   R² represents a straight chain or branched chain C2 to C12            saturated hydrocarbon chain, and        -   X² represents a hydrogen atom or a straight chain or            branched chain C1 to C6 alkyl group.

In one preferred embodiment of the present invention, the treatmentliquid comprises at least a cyclic ester compound of formula (1) and amain solvent.

In one preferred embodiment of the present invention, the treatmentliquid comprises at least a cyclic amide compound of formula (2) and amain solvent.

In a preferred embodiment of the present invention, the main solvent inthe treatment liquid is water.

Further, in a preferred embodiment of the present invention, thetreatment liquid further comprises a surfactant and/or an organicsolvent having low surface tension.

According to the present invention, there is provided a method for inkjet recording, comprising coating a treatment liquid onto a recordingmedium having a recording face formed of a plastic film, then ejectingdroplets of an ink composition and depositing the droplets onto therecording face to perform printing, wherein said treatment liquid is atreatment liquid for a plastic film according to the present invention,and said ink composition is a water-based pigment ink compositioncomprising at least a pigment, a thermoplastic resin, and water.

According to a second aspect of the present invention, there is provideda primer liquid for printing on an ink jet recording medium having arecording face formed of a plastic film, wherein said primer liquidcomprising at least

a heterocyclic ketone compound selected from the group consisting ofcyclic ester compounds of formula (1), cyclic amide compound of formula(2), and a combination thereof,

a thermoplastic resin, and

a main solvent,

said thermoplastic resin being dispersed in said primer liquid.

In one preferred embodiment of the present invention, the primer liquidfor printing comprises at least a cyclic ester compound of formula (1),a thermoplastic resin, and a main solvent, the thermoplastic resin beingdispersed in the primer liquid.

In one preferred embodiment of the present invention, the primer liquidfor printing comprises at least a cyclic amide compound of formula (2),a thermoplastic resin, and a main solvent, the thermoplastic resin beingdispersed in the primer liquid.

In a preferred embodiment of the present invention, the main solvent inthe primer liquid is water.

Further, in a preferred embodiment of the present invention, the primerliquid further comprises a surfactant and/or an organic solvent havinglow surface tension.

According to the present invention, there is provided a set for ink jetrecording, comprising a water-based pigment ink composition comprisingat least a primer liquid according to the present invention, a pigment,a thermoplastic resin, and water.

According to the present invention, there is provided a method for inkjet recording, comprising coating a primer liquid onto a recordingmedium having a recording face formed of a plastic film to form a primerfilm and then ejecting and depositing droplets of an ink compositiononto the primer film to perform printing, wherein said primer liquid isa primer liquid for printing according to the present invention, andsaid ink composition is a water-based pigment ink composition comprisingat least a pigment, a thermoplastic resin, and water.

According to a third aspect of the present invention, there is providedan ink composition for an ink jet recording medium having a recordingface formed of a plastic film, wherein said ink composition comprising

a heterocyclic ketone compound selected from the group consisting ofcyclic ester compounds of formula (1), cyclic amide compound of formula(2), and a combination thereof,

a thermoplastic resin,

a colorant, and

a main solvent,

said thermoplastic resin being dispersed in said ink composition.

In a preferred embodiment of the present invention, the ink compositionfurther comprises a cyclic ether compound of formula (3):

-   -   wherein        -   R′ represents a straight chain or branched chain C2 to C12            saturated hydrocarbon chain or a straight chain or branched            chain C2 to C12 saturated ether chain.

In a preferred embodiment of the present invention in the inkcomposition, the colorant is a pigment and is dispersed in the inkcomposition.

In a preferred embodiment of the present invention, the main solvent inthe ink composition is water.

Further, in a preferred embodiment of the present invention, the inkcomposition further comprises a surfactant and/or a low-surface tensionorganic solvent.

According to the present invention, there is provided a method for inkjet recording, characterized by comprising ejecting and depositingdroplets of an ink composition onto a recording medium having arecording face of a plastic film to perform printing, wherein said inkcomposition is an ink composition according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

I. Treatment Liquid

According to one aspect of the present invention, there is provided atreatment liquid for an ink jet recording medium having a recording faceformed of a plastic film.

As described above, the treatment liquid according to the presentinvention is a treatment liquid for an ink jet recording medium having arecording face formed of a plastic film and comprises at least aheterocyclic ketone compound selected from the group consisting ofcyclic ester compounds of formula (1), cyclic amide compound of formula(2), and a combination thereof and a main solvent. As described below,the main solvent is preferably water. Preferably, the treatment liquidaccording to the present invention further comprises a surfactant and/ora low-surface tension organic solvent. More preferably, the treatmentliquid according to the present invention further comprises a surfactantor further comprises a surfactant and a low-surface tension organicsolvent. Further, preferably, the treatment liquid according to thepresent invention is coated onto the recording medium by ink jetrecording.

The treatment liquid according to the present invention is used forprinting on a recording face formed of a plastic film.

In the present invention, recording media having a recording face formedof a plastic film include plastic films which per se constitute therecording medium, and, further, recording media comprising a plasticcoated onto conventional recording medium base materials such as paper,and recording media comprising a plastic film bonded onto the basematerial.

Further, in the present invention, the plastic is not particularlylimited so far as it is dissolved in or can be brought to a wetted stateby a heterocyclic ketone compound. Examples thereof include polyvinylchloride, polyethylene terephthalate (PET), polycarbonate, polystyrene,and polyurethane. In the present invention, the plastic is preferablypolyvinyl chloride.

The treatment liquid according to the present invention can be used forprinting on non-surface-treated plastic films for ink jet printing, aswell as surface-treated plastic films for ink jet printing.

The treatment liquid according to the present invention, when used withthe water-based ink composition comprising the thermoplastic resin, canform a plastic recorded matter possessing excellent rubbing resistance,scratch resistance, and waterfastness. In this case, the ink compositionis a water-based pigment ink composition comprising at least a pigment,a thermoplastic resin, and water. Therefore, in the present invention,since a pigment-type water-based ink composition can be used, recordedmatters possessing excellent lightfastness can be formed on plasticfilms.

The reason for which the desired effect can be attained by the presentinvention is considered as follows. However, it should be noted that thefollowing reason is hypothetical and should not be construed as limitingthe present invention.

Upon coating onto a plastic film, the treatment liquid according to thepresent invention is spread evenly on the surface of the plastic film.When water is evaporated in this state, the heterocyclic ketone compoundcan be allowed to stay homogeneously in a high concentration on thesurface of the plastic film. Consequently, it is considered that theheterocyclic ketone compound can bring a very shallow part from thesurface of the plastic film to a dissolved or wetted state. Thereafter,when a water-based ink containing a resin which can be brought to a filmupon heating is deposited on the coating followed by curing of the resincontained in the water-based ink to form a film, it is considered that alayer formed of a mixture of the resin contained in the water-based inkwith the plastic is formed at the interface of the cured film and theplastic. It is considered that, since this mixed layer is integral withthe plastic as well as with the film formed by curing of the resincontained in the ink, the adhesion between the ink layer and the plasticsurface can be significantly improved. The enhanced adhesion cansubstantially prevent the separation of the film caused, for example, byexternal force such as friction or the entry of water into the interfaceand thus can realize the formation of plastic recorded matterspossessing excellent rubbing resistance, scratch resistance and waterresistance. Thus, the preparation of strong printed matters utilizingthe durability of the plastic film per se can be realized.

In the treatment liquid according to the present invention, preferably,since the heterocyclic ketone compound, which is a component capable ofdissolving the plastic, has been diluted with water, there issubstantially no possibility that the treatment liquid breaks or damagemembers constituting the printer with which the liquid comes intocontact. Further, since a preferred treatment liquid according to thepresent invention is in an aqueous solution form, the treatment liquidper se and vapor generated from the treatment liquid are also highlysafe.

I-1. Heterocyclic Ketone Compound

The treatment liquid according to the present invention comprises aheterocyclic ketone compound as an indispensable component.

The term “heterocyclic ketone compound” as used herein refers to aheterocyclic ketone compound selected from the group consisting ofcyclic ester compounds of formula (1), cyclic amide compounds of formula(2), and a combination thereof. Accordingly, the heterocyclic ketonecompound may be, for example, any one of or a combination of a pluralityof compounds belonging to the cyclic ester compounds of formula (1) oralternatively may be a combination of a compound selected from cyclicester compounds of formula (1) with a compound selected from cyclicamide compound of formula (2). In a preferred embodiment of the presentinvention, the heterocyclic ketone compound is either a cyclic estercompound of formula (1) or a cyclic amide compound of formula (2).

I-1-1. Cyclic Ester Compound

In formula (1), as described above, R¹ represents a straight chain orbranched chain C2 to C12 saturated hydrocarbon chain, and X¹ represents—CH₂— or —O—. R¹ preferably represents C2 to C8, more preferably C2 toC5, still more preferably C2 to C4, saturated hydrocarbon chain. Here,for example, “C2 to C12” in “C2 to C12 saturated hydrocarbon chain”means that the number of carbon atoms in the saturated hydrocarbon chainis 2 to 12.

In formula (1), the straight chain C2 to C12 saturated hydrocarbon chainrefers to a chain represented by —(CH₂)m- wherein m is an integer of 2to 12. The branched chain C2 to C12 saturated hydrocarbon chain refersto a chain, represented by —(CH₂)n-, having a side chain(s) provided bysubstituting a hydrogen atom(s) on the carbon atom by one or more alkylgroups so that the total number of carbon atoms is p, provided that n+p,wherein p represents the total number of carbon atoms on all the sidechains is an integer of 2 to 12. Such alkyl substituents include, forexample, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, andt-butyl. The saturated hydrocarbon chain on the straight chain orbranched chain may if necessary be further substituted, for example, bya hydroxyl group or hydroxymethylene.

Specific examples of straight chain or branched chain C2 to C12saturated hydrocarbon chains include ethylene and propylene.

Specific examples of cyclic ester compounds include γ-butyrolactone,ε-caprolactone, δ-hexanolactone, propylene carbonate, ethylenecarbonate, and 1,3-dioxan-2-one. The cyclic ester compound is preferablyselected from the group consisting of γ-butyrolactone, ε-caprolactone,propylene carbonate, and ethylene carbonate. More preferably, the cyclicester compound is γ-butyrolactone or propylene carbonate.

In the present invention, one cyclic ester compound or a mixture of atleast two cyclic ester compounds may be used. The cyclic ester compoundused in the present invention may if necessary be synthesized, oralternatively may be a commercially available product.

I-1-2. Cyclic Amide Compound

In formula (2), as described above, R² represents a straight chain orbranched chain C2 to C12 saturated hydrocarbon chain, and X² representsa hydrogen atom or a straight chain or branched chain C1 to C6 alkylgroup.

R² preferably represents C2 to C8, more preferably C2 to C5, still morepreferably C2 to C4, saturated hydrocarbon chain. Here, for example, “C2to C12” in “C2 to C12 saturated hydrocarbon chain” means that the numberof carbon atoms in the saturated hydrocarbon chain is 2 to 12.

In formula (2), the straight chain C2 to C12 saturated hydrocarbon chainrefers to a chain represented by —(CH₂)m- wherein m is an integer of 2to 12. The branched chain C2 to C12 saturated hydrocarbon chain refersto a chain, represented by —(CH₂)n-, having a side chain(s) provided bysubstituting a hydrogen atom(s) on the carbon atom by one or more alkylgroups so that the total number of carbon atoms is p, provided that n+p,wherein p represents the total number of carbon atoms on all the sidechains, is an integer of 2 to 12. Such alkyl substituents include, forexample, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, andt-butyl. The saturated hydrocarbon chain on the straight chain orbranched chain may if necessary be further substituted, for example, bya hydroxyl group or hydroxymethylene.

Specific examples of straight chain or branched chain C2 to C12saturated hydrocarbon chains include ethylene and propylene.

Here “C1 to C6” in the case of “C1 to C6 alkyl group” in the “straightchain or branched chain C1 to C6 alkyl group” means that the number ofcarbon atoms in the alkyl group is 1 to 6. Examples of alkyl groupsinclude methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl,t-butyl, pentyl, and hexyl groups.

In formula (2), “C1 to C6 alkyl” preferably represents a C1 to 4 alkylgroup, more preferably a C1 to C3 alkyl group, still more preferably amethyl or ethyl group, particularly preferably a methyl group.

In a preferred embodiment of the present invention, in formula (2), R²represents a straight chain or branched chain C2 to C5 saturatedhydrocarbon group and X² represents a hydrogen atom or a methyl group.

Specific examples of cyclic amide compounds include 2-pyrrolidone,N-methyl-2-pyrrolidone, 5-methyl-2-pyrrolidone, δ-valerolactam, andε-caprolactam. The cyclic amide compound is preferably selected from thegroup consisting of 2-pyrrolidone, N-methyl-2-pyrrolidone, andε-caprolactam.

In a preferred embodiment of the present invention, at least two cyclicamide compounds of formula (2) are used. The separation orcrystallization of the cyclic amide compound in the course of theevaporation of the solvent in the treatment liquid can be prevented byusing two or more cyclic amide compounds. The use of two or more cyclicamide compounds can enhance the solubility of the cyclic amide compoundin the treatment liquid solvent and can prevent the occurrence of anunfavorable phenomenon that the cyclic amide compound is presentunevenly on the surface of the plastic and, consequently, the capabilityof dissolving the plastic is partially changed.

Specific preferred examples of the use of two or more cyclic amidecompounds include a combination of 2-pyrrolidone with ε-caprolactam, acombination of N-methyl-2-pyrrolidone with ε-caprolactam, a combinationof 2-pyrrolidone with N-methyl-2-pyrrolidone, and a combination of2-pyrrolidone with N-methyl-2-pyrrolidone and ε-caprolactam.

The cyclic amide compound used in the present invention may if necessarybe synthesized or alternatively may be a commercially available product.

The content of the heterocyclic ketone compound in the treatment liquidaccording to the present invention is not particularly limited so far asit can bring the treatment liquid to such concentration and surfacetension that the treatment liquid can be coated evenly onto therecording medium, and there is no possibility that members constitutingthe printer with which the liquid comes into contact are notsubstantially broken or damaged. The content of the heterocyclic ketonecompound is, for example, 0.1 to 50.0% by weight, preferably 5.0 to30.0% by weight based on the total amount of the treatment liquid. Whentwo or more cyclic amide compounds are used, the content refers to thetotal content of the two or more compounds. Further, this is true of thecase where a combination of the cyclic ester compound and the cyclicamide compound is used.

I-2. Surfactant

The aqueous solution is usually repelled by plastics. Since, however, asurfactant and/or a low-surface tension organic solvent can be added tothe treatment liquid according to the present invention, theheterocyclic ketone compound can be coated evenly on the plasticsurface. It is considered that, upon the evaporation of water from theevenly coated treatment liquid, the heterocyclic ketone compound isfixed adequately on the surface of the plastic and can dissolve theplastic surface only in its desired area.

In the present invention, any of anionic, cationic, amphoteric and/ornonionic surfactants may be used.

Anionic surfactants include, for example, alkylsulfocarbonates,α-olefinsulfonates, polyoxyethylene alkyl ether acetates, N-acylaminoacid and its salts, N-acylmethyltaurine salts, alkylsulfate polyoxyalkylether sulfates, alkylsulfate polyoxyethylene alkyl ether phosphates,rosin acid soaps, castor oil sulfuric ester salts, lauryl alcoholsulfuric ester salts, alkylphenol-type phosphotric acid esters,alkyl-type phosphoric acid esters, alkylarylsulfonic acid salts,diethylsulfosuccinic acid salts, diethylhexylsulfosuccinic acid salts,dioctylsulfosuccinic acid salts, and 2-vinylpyridine derivatives andpoly-4-vinylpyridine derivatives.

Specific examples of amphoteric surfactants includelauryldimethylaminoacetic acid betaine,2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oilfatty acid amide propyldimethylaminoacetic acid betaine,polyoctylpolyaminoethylglycine, and imidazoline derivatives.

Specific examples of nonionic surfactants usable herein include ethersurfactants, such as polyoxyethylene nonylphenyl ether, polyoxyethylenedodecylphenyl ether, polyoxyethylene alkylallyl ether, polyoxyethylenealeyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether,and polyoxyalkylene alkyl ether, polyoxyethyleneoleic acid ester, estersurfactants, such as polyoxyethyleneoleic ester,polyoxyethylenedistearic ester, sorbitan laurate, sorbitan monostearate,sorbitan rnonooleate, sorbitan sesquioleate, polyoxyethylenernonooleate, and polyoxyethylene stearate, or acetylene glycolsurfactants represented by formula (i):

wherein R¹¹, R¹², R¹³ and R¹⁴ each independently represent an alkylgroup having 1 to 6 carbon atoms; and n and m are each an integer whichbrings the sum of n and m to 0 to 30, for example,2,4,7,9-tetramethyl-5-decyne-4,7-diol (for example, Surfynol 104,manufactured by Air Products and Chemicals. Inc.),3,6-dimethyl-4-octyne-3,6-diol (for example, Surfynol 82, manufacturedby Air Products and Chemicals. Inc.), and derivatives of these acetyleneglycols (for example, Surfynol 465 and Surfynol 485 manufactured by AirProducts and Chemicals. Inc.).

Among them, nonionic surfactants having good foaming properties orreliability of ejection through nozzles are preferred, and acetyleneglycol surfactants are more preferred.

The content of the surfactant in the treatment liquid according to thepresent invention is not particularly limited so far as the heterocyclicketone compound can be coated evenly on the plastic surface, and thecontent of the surfactant can be properly selected depending upon thetype of the surfactant used and the type and amount of the heterocyclicketone compound. The content of the surfactant may be, for example, 0.01to 5.0% by weight, preferably 0.1 to 2.0% by weight, based on the totalamount of the treatment liquid.

I-3. Low-Surface Tension Organic Solvent

In order to coat the heterocyclic ketone compound evenly on the plasticsurface, the treatment liquid according to the present invention maycontain a low-surface tension organic solvent instead of or in additionto the surfactant.

Examples of low-surface tension organic solvents include monohydricalcohols or polyhydric alcohol derivatives.

Monohydric alcohols particularly having 1 to 4 carbon atoms, forexample, methanol, ethanol, n-propanol, i-propanol, or n-butanol, may beused as the monohydric alcohol.

In particular, full or partial ethers of a di- to tetrahydric alcoholhaving 2 to 6 carbon atoms and a lower alcohol having 1 to 4 carbonatoms may be used as the polyhydric alcohol derivative. The polyhydricalcohol derivative is an alcohol derivative, in which at least onehydroxyl group has been etherized, but does not mean etherized hydroxylgroup-free polyhydric alcohol per se. The polyhydric alcohol lower alkylether which is preferred as the ether, is a compound represented bygeneral formula (ii):

R²¹O—[CH₂—CH(R²³)—O]t—R²²  (ii)

wherein R²¹ and R²² each independently represent a hydrogen atom or analkyl group having 3 to 6 carbon atoms, preferably a butyl group; R²³represents a hydrogen atom or a lower alkyl group having 1 to 4 carbonatoms, preferably a hydrogen atom or a methyl or ethyl group; and t isan integer of 1 to 8, preferably 1 to 4, provided that at least one ofR²¹ and R²² is an alkyl group having 3 to 6 carbon atoms, preferably abutyl group.

Specific examples of polyhydric alcohol lower alkyl ethers includemono-, di- or triethylene glycol-mono- or dialkylene ether, and mono-,di- or tripropylene glycol-mono- or dialkyl ether. Preferred aretriethylene glycol monobutyl ether, diethylene glycol monobutyl ether,diethylene glycol monopropyl ether, diethylene glycol monopentyl ether,and propylene glycol monobutyl ether.

In a preferred embodiment of the present invention, the low-surfacetension organic solvent is diethylene glycol monobutyl ether ortriethylene glycol monobutyl ether.

The content of the low-surface tension organic solvent in the treatmentliquid according to the present invention is not particularly limited,so far as the heterocyclic ketone compound can be evenly coated onto thesurface of plastic, and may be properly selected according to theheterocyclic ketone compound used and the kind and amount of thesurfactant. The content of the low-surface tension organic solvent maybe, for example, 0 to 25.0% by weight, preferably 2.0 to 15.0% byweight, based on the total amount of the treatment liquid.

Various properties of the treatment liquid according to the presentinvention can be properly regulated. In a preferred embodiment of thepresent invention, the viscosity of the treatment liquid is preferablynot more than 25 mPa·sec, more preferably not more than 10 mPa·sec (25°C.). When the viscosity is in this range, the treatment liquid can bestably ejected through an ink ejection head. Further, the surfacetension of the treatment liquid according to the present invention canbe properly regulated and is preferably approximately in the range of20.0 to 40.0 mN/m (25° C.), more preferably approximately in the rangeof 25.0 to 35.0 mN/m.

I-4. Main Solvent

The treatment liquid according to the present invention contains a mainsolvent. In order to coat a heterocyclic ketone compound-containingwater-soluble component thinly and evenly on the surface of plastic, inthe present invention, the heterocyclic ketone compound is diluted witha main solvent before coating. For example, water or a water-solubleorganic solvent is usable as the main solvent. In the present invention,water is preferred, for example, from the viewpoint of safety.

Accordingly, in the treatment liquid according to the present invention,the main solvent is preferably water. Water may be pure water obtainedby ion exchange, ultrafiltration, reverse osmosis, distillation or thelike, or ultrapure water from the viewpoint of minimizing ionicimpurities. Water, which has been sterilized, for example, byultraviolet irradiation or by addition of hydrogen peroxide, issuitable, because this treatment can prevent the growth of mold orbacteria and, thus, the treatment liquid can be stored for a long periodof time.

I-5. Other Ingredients

When the treatment liquid according to the present invention containsthe above ingredients, a desired effect can be attained. If necessary,the treatment liquid may further comprise preservatives or fungicides,pH adjustors, dissolution aids, antioxidants, nozzle clogging preventiveagents and the like.

pH adjustors include, for example, potassium dihydrogenphosphate orsodium dihydrogenphosphate. Specific examples of preservatives andfungicides include sodium benzoate, pentachlorophenol sodium,2-pyridinethiol-1-oxide sodium, sodium sorbate, sodium dehydroacetate,and 1,2-dibenzisothiazolin-3-one (Proxel CRL, Proxel BDN, Proxel GXL,Proxel XL-2, and Proxel TN, manufactured by ICI). Examples ofdissolution aids or antioxidants include: amines such as diethanolamine,triethanolamine, propanolamine, and morpholine, and modificationproducts thereof; inorganic salts such as potassium hydroxide, sodiumhydroxide, and lithium hydroxide; ammonium hydroxide; quaternaryammonium hydroxide such as tetramethylammonium; salts of carbonic acidsuch as potassium carbonate, sodium carbonate, and lithium carbonate;salts of phosphoric acid such as potassium phosphate, sodium phosphate,and lithium phosphate; N-methyl-2-pyrrolidone; urea compounds such asurea, thiourea, and tetramethylurea; allophanates such as allophanateand methyl allophanate; biurets such as biuret, dimethylbiuret, andtetramethylbiuret; and L-ascorbic acid and salts thereof. Further, forexample, urea, thiourea, or ethylene urea may be added to prevent nozzledrying.

I-6. Production of Treatment Liquid

The treatment liquid according to the present invention may be preparedby properly mixing the above ingredients together in any order todissolve (or disperse) them and if necessary removing impurities and thelike by filtration.

In the treatment liquid according to the present invention, the mixingamounts of the above ingredients can be properly determined so as tosatisfy requirements, for example, that the water-based ink compositiondeposited after the deposition of the treatment liquid has high adhesionto the surface of plastic; the heterocyclic ketone compound can beevenly coated onto the surface of plastic; the viscosity and surfacetension are such that the treatment liquid can be ejected through an inkjet recording head; the treatment liquid is not coagulated or solidifiedin a storage container or in nozzles in an ink jet head; and members incontact with liquids in an ink jet printer are not dissolved in orbroken by the treatment liquid. For example, the treatment liquidtypically has the following composition:

Heterocyclic ketone compound 0.1 to 50.0 wt % Surfactant 0.01 to 5.0 wt% Low-surface tension organic solvent   0 to 25.0 wt % Water Balance.

Accordingly, in one preferred embodiment of the present invention, inthe treatment liquid, the content of the heterocyclic ketone compound is0.1 to 50.0% by weight, and the content of the surfactant is 0.01 to5.0% by weight.

I-7. Recording Method Using Treatment Liquid

As described above, the method for ink jet recording according to thefirst aspect of the present invention comprises coating a treatmentliquid onto a recording medium having a recording face formed of aplastic film, then ejecting droplets of an ink composition anddepositing the droplets onto the recording face to perform printing.

In the step of coating a treatment liquid, the treatment liquidaccording to the present invention is coated onto a recording medium inits recording face. In this step, preferably, the treatment liquid ispreviously coated onto at least a part (a printing part) into which thewater-based pigment ink is implanted in the next ink jet recording step.The coverage can be properly regulated depending, for example, upon thestate of the plastic film as the recording medium and the type of thematerial of the plastic film, and the implantation amount of ink.

In the present invention, the treatment liquid may be coated by anymethod without particular limitation, and examples of coating methodsinclude brush coating, or contact-type coating using a conventionalcoating device such as an air knife coater, a roll coater, a bar coater,a blade coater, a slide hopper coater, a gravure coater, a flexogravurecoater, a curtain coater, an extrusion coater, a floating knife coater,a Komma coater, a die coater, gate roll coater, or a size press, andnon-contact-type coating using a spray, an ink jet head, a jet nozzle orthe like.

In the present invention, preferably, the treatment liquid may be coatedby an ink jet recording method in which droplets of the treatment liquidare ejected and deposited onto the recording medium in its recordingface. When the ink jet recording method is adopted, the coating positionand coating amount of the treatment liquid can be properly controlled.The treatment liquid can be coated only onto the part to be printed bycontrolling the coating position. Accordingly, the amount of thetreatment liquid used can be saved, and, when the treatment liquid isprinted on the edge of the plastic recording medium, it is possible toprevent the treatment liquid from running over from the plasticrecording medium. When a large amount of solvent is coated onto theplastic recording medium, the whole plastic is dissolved or softened.However, the plastic recording medium only in its very shallow part fromthe surface of the plastic recording medium can be selectively dissolvedby controlling the coating amount.

In a preferred embodiment of the present invention, the ink jetrecording method according to the first aspect of the present inventionfurther comprises, before the deposition of the ink composition, adrying step of evaporating water from the coated treatment liquid toevaporate a part of the heterocyclic ketone compound. Evaporation of apart of the heterocyclic ketone compound in the treatment liquid meansthat the heterocyclic ketone compound is evaporated in the treatmentliquid on the coated face so that, when the ink composition is depositedonto the treatment liquid coating face, the treatment liquid coated faceis not in a fully dried state and the plastic surface dissolved state ismaintained. The amount of the heterocyclic ketone compound necessary forrealizing this dissolved state (or the amount of the heterocyclic ketonecompound to be evaporated) may be properly varied by regulating dryingconditions while taking into consideration the level of adhesion betweenthe film to be formed by the ink composition and the plastic surface.

After coating the treatment liquid, drying for removing water can becarried out by a conventional method using conventional heat dryingmeans, for example, a conventional heating device such as an infraredheating device or a hot air heating device. In the present invention,preferably, drying treatment in the drying step can be carried out byheating with a heater or hot-air drying. In the case of heating with aheater or hot-air drying, the drying can be carried out at 25 to 90° C.(preferably 40 to 70° C.) for 1 to 60 min.

Next, in the ink jet recording method according to the first aspect ofthe present invention, after coating the treatment liquid, an inkcomposition is deposited on the coating face. In this case, preferably,ink is deposited by an ink jet recording method. Further, the inkcomposition referred to herein is a water-based pigment ink compositioncomprising at least a pigment, a thermoplastic resin, and water whichwill be described later.

In a preferred embodiment of the present invention, the ink jetrecording method according to the first aspect of the present inventionfurther comprises the step of heating the ink composition deposited onthe recording face to form a resin film. The heating means can becarried out by a conventional method using a conventional heating devicesuch as an infrared heating device or a hot air heating device. In thepresent invention, preferably, heating treatment in the heating step canbe carried out by heating with a heater or hot-air drying. The heatingmay be carried out under such conditions that the resin contained in theink composition is cured by heating to form a resin film, and theheating conditions may be properly determined by taking intoconsideration, for example, the type of resin particles. For example, inthe case of heating with a heater or hot-air drying, the heating can becarried out at 25 to 90° C. (preferably 40 to 70° C.) for one min to onedays (preferably 2 min to 16 hr).

I-8. Water-Based Pigment Ink Composition to be Used in Combination withTreatment Liquid

The water-based pigment ink composition usable in the first aspect ofthe present invention comprises at least a pigment, a thermoplasticresin, and water.

I-8-1. Pigment

In the present invention, the water-based pigment ink composition maycontain any desired pigment that has hitherto been used in water-basedink compositions for ink jet recording. Examples of pigments includeorganic pigments or inorganic pigments which have hitherto been used inink compositions for ink jet recording. The pigment may be added, to theink composition, as a resin dispersed pigment comprising a pigment whichhas been dispersed together with a dispersant such as a water solubleresin or a surfactant, or as a surface treatment pigment comprising apigment which could have been rendered dispersible or dissolvable in awater-based medium without use of any dispersant by introducing ahydrophilic group into the pigment surface. When the pigment isdispersed with the aid of a resin dispersant, a thermoplastic resin,which will be described later, may be used as a thermoplastic resindispersant. Two or more pigments may be used in combination.

Inorganic pigments usable herein include titanium oxide, iron oxide, andcarbon blacks produced by conventional processes such as contact,furnace, and thermal processes.

Organic pigments usable herein include azo pigments (including azo lake,insoluble azo pigment, condensed azo pigment, and chelate azo pigment),polycyclic pigments (for example, phthalocyanine, perylene, perinone,anthraquinone, quinacridone, dioxazine, thioindigo, isoindolinone, andquinophthalone pigments), dye chelates (for example, basic dye chelatesand acid dye chelates), nitro pigments, nitroso pigments, and anilineblack. Among these pigments, pigments having good affinity for water arepreferred.

More specifically, pigments for black ink include, for example, carbonblacks (C.I. Pigment Black 7) such as furnace black, lamp black,acetylene black, or channel black, metal oxides such as copper oxide,iron oxide (C.I. Pigment Black 11), and titanium oxide, and organicpigments such as aniline black (C.I. Pigment Black 1).

Specific examples of suitable carbon blacks include: carbon blacksmanufactured by Mitsubishi Chemical Corporation, for example, No. 2300,No. 900, MCF 88, No. 20B, No. 33, No. 40, No. 45, No. 52, MA 7, MA 8, MA100, and No. 2200 B; carbon blacks manufactured by Degussa, for example,ColorBlack FW1, ColorBlack FW2, ColorBlack FW2V, ColorBlack FW18,ColorBlack FW200, ColorBlack S150, ColorBlack S160 and ColorBlack S170,Pritex 35, Pritex U, Pritex V and Pritex 140U, Special Black 6, SpecialBlack 5, Special Black 4A, Special Black 4 and Special Black 250; carbonblacks manufactured by Columbian Carbon Co., Ltd., for example,CONDUCTEX SC, Raven 1255, Raven 5750, Raven 5250, Raven 5000, Raven3500, Raven 1255, and Raven 700; and carbon blacks manufactured by CabotCorporation, for example, Regal 400 R, Regal 330 R, Regal 660 R, MogulL, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000,Monarch 1100, Monarch 1300, Monarch 1400, and Elftex 12.

Pigments for color inks include C.I. Pigment Yellow 1 (Fast Yellow G),C.I. Pigment Yellow 3, C.I. Pigment Yellow 12 (Disazo Yellow AAA), C.I.Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 17, C.I.Pigment Yellow 23, C.I. Pigment Yellow 24, C.I. Pigment Yellow 34, C.I.Pigment Yellow 35, C.I. Pigment Yellow 37, C.I. Pigment Yellow 42(yellow iron oxide), C.I. Pigment Yellow 53, C.I. Pigment Yellow 55,C.I. Pigment Yellow 74, C.I. Pigment Yellow 81, C.I. Pigment Yellow 83(Disazo Yellow HR), C.I. Pigment Yellow 95, C.I. Pigment Yellow 97, C.I.Pigment Yellow 98, C.I. Pigment Yellow 100, C.I. Pigment Yellow 101,C.I. Pigment Yellow 104, C.I. Pigment Yellow 108, C.I. Pigment Yellow109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 117, C.I. PigmentYellow 120, C.I. Pigment Yellow 138, C.I. Pigment Yellow 153, and C.I.Pigment Yellow 154; C.I. Pigment Red 1, C.I. Pigment Red 2, C.I. PigmentRed 3, C.I. Pigment Red 5, C.I. Pigment Red 17, C.I. Pigment Red 22(Brilliant Fast Scarlet), C.I. Pigment Red 23, C.I. Pigment Red 31, C.I.Pigment Red 38, C.I. Pigment Red 48:2 (Permanent Red 2B(Ba)), C.I.Pigment Red 48:2 (Permanent Red 2B(Ca)), C.I. Pigment Red 48:3(Permanent Red 2B(Sr)), C.I. Pigment Red 48:4 (Permanent Red 2B(Mn)),C.I. Pigment Red 49:1, C.I. Pigment Red 52:2, C.I. Pigment Red 53:1,C.I. Pigment Red 57:1 (Brilliant Carmine 6B), C.I. Pigment Red 60:1,C.I. Pigment Red 63:1, C.I. Pigment Red 63:2, C.I. Pigment Red 64:1,C.I. Pigment Red 81 (Rhodamine 6G Lake), C.I. Pigment Red 83, C.I.Pigment Red 88, C.I. Pigment Red 92, C.I. Pigment Red 101 (red oxide),C.I. Pigment Red 104, C.I. Pigment Red 105, C.I. Pigment Red 106, C.I.Pigment Red 108 (cadmium red), C.I. Pigment Red 112, C.I. Pigment Red114, C.I. Pigment Red 122 (quinacridone magenta), C.I. Pigment Red 123,C.I. Pigment Red 146, C.I. Pigment Red 149, C.I. Pigment Red 166, C.I.Pigment Red 168, C.I. Pigment Red 170, C.I. Pigment Red 172, C.I.Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 179, C.I.Pigment Red 185, C.I. Pigment Red 190, C.I. Pigment Red 193, C.I.Pigment Red 209 and C.I. Pigment Red 219; or C.I. Pigment Blue 1, C.I.Pigment Blue 2, C.I. Pigment Blue 15 (Phthalocyanine Blue R), C.I.Pigment Blue 15:1, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3(Phthalocyanine Blue G), C.I. Pigment Blue 15:4, C.I. Pigment Blue 15:6(Phthalocyanine Blue E), C.I. Pigment Blue 16, C.I. Pigment Blue 17:1,C.I. Pigment Blue 56, C.I. Pigment Blue 60 and C.I. Pigment Blue 63; andthe like.

The particle diameter of the pigment is not particularly limited.Preferably, however, the average particle diameter is not more than 25μm, more preferably not more than 1 μm. When the pigment has an averageparticle diameter of not more than 25 μm, the occurrence of clogging canbe suppressed and more satisfactory ejection stability can be realized.

The content of the pigment is preferably 0.5 to 25% by weight, morepreferably 2 to 15% by weight, based on the whole water-based pigmentink composition.

I-8-2. Thermoplastic Resin

In the first aspect of the present invention, the water-based pigmentink composition comprises a thermoplastic resin.

Resins soluble or insoluble in water-based ink media may be used as thethermoplastic resin. The above resin dispersant used in the dispersionof the pigment is suitable as the resin soluble in the water-based inkmedium. Regarding the resin insoluble in the water-based ink medium,preferably, resin particles are added in a resin emulsion form to theink composition. The resin emulsion comprises water as a continuousphase and a resin component (a thermoplastic resin component) as adispersed phase.

In a preferred embodiment of the present invention, the thermoplasticresin is a polymer that has a hydrophilic moiety and a hydrophobicmoiety in combination. When the resin emulsion is used as thethermoplastic resin, the particle diameter is not particularly limitedso far as an emulsion is formed. Preferably, however, the particlediameter is about not more than 150 nm, more preferably about 5 to 100nm.

The same resin component as in the dispersant resins or resin emulsions,which have hitherto been used in ink compositions for ink jet recording,may be used as the thermoplastic resin. Specific examples ofthermoplastic resins usable herein include acrylic polymers, forexample, polyacrylic esters or copolymers thereof, polymethacrylicesters or copolymers thereof, polyacrylonitrile or copolymers thereof,polycyanoacrylate, polyacrylamide, polyacrylic acid, or polymethacrylicacid; polyolefin polymers, for example, polyethylene, polypropylene,polybutene, polyisobutylene, polystyrene, or copolymers thereof,petroleum resins, cumarone-indene resins, or terpene resins; vinylacetate-vinyl alcohol polymers, for example, polyvinyl acetate orcopolymers thereof, polyvinyl alcohol, polyvinyl acetal, or polyvinylether; halogen-containing polymers, for example, polyvinyl chloride orcopolymers thereof, polyvinylidene chloride, fluororesins, orfluororubbers; nitrogen-containing vinyl polymers, for example,polyvinylcarbazole, polyvinylpyrrolidone or copolymers thereof,polyvinylpyridine, or polyvinylimidazole; diene polymers, for example,polybutadiene or copolymers thereof, polychloroprene, or polyisoprene(butyl rubbers); or other ring opening polymerization-type resins,condensation polymerization-type resins, or naturally occurring polymerresins.

When the thermoplastic resin is provided in an emulsion form, theemulsion may be prepared by mixing resin particles, optionally togetherwith a surfactant, into water. For example, an emulsion of an acrylicresin or a styrene-acrylic acid copolymer resin can be prepared bymixing an (meth)acrylic ester resin or a styrene-(meth)acrylic esterresin and optionally an (meth)acrylic acid resin and a surfactant intowater. In general, the mixing ratio between the resin component and thesurfactant is preferably about 50:1 to 5:1. When the amount of thesurfactant used is below the lower limit of the above-defined amountrange, emulsion is less likely to be formed. On the other hand, when theamount of the surfactant used is above the upper limit of theabove-defined amount range, disadvantageously, there is a tendency thata deterioration in waterfastness of the ink or a deterioration inadhesion occurs.

The surfactant used in the preparation of the resin emulsion is notparticularly limited. Preferred surfactants include anionic surfactants,for example, sodium dodecylbenzenesulfonate, sodium laurylate, andammonium salt of polyoxyethylene alkyl ether sulfate, nonionicsurfactants, for example, polyoxyethylene alkyl ether, polyoxyethylenealkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylenealkyl phenyl ether, polyoxyethylene alkylamine, and polyoxyethylenealkylamide. They may also be used as a mixture of two or more.

The emulsion of the thermoplastic resin may also be produced by emulsionpolymerizing the monomer of the above resin component in water in thepresence of a polymerization catalyst and an emulsifier. Apolymerization initiator, an emulsifier, and a molecular weight modifierused in the emulsion polymerization may be used by a conventionalmethod.

The polymerization initiator may be the same as used in the conventionalradical polymerization, and examples thereof include potassiumpersulfate, ammonium persulfate, hydrogen peroxide,azobisisobutyronitrile, benzoyl peroxide, dibutyl peroxide, peraceticacid, cumene hydroperoxide, t-butyl hydroxyperoxide, and p-menthanehydroxyperoxide. When the polymerization reaction is carried out inwater, the use of a water soluble polymerization initiator is preferred.For example, in additon to sodium laurylsulfate, compounds which havebeen generally used as anionic surfactants, nonionic surfactants oramphoteric surfactants, and mixture of these surfactants, may bementioned as the emulsifier. A mixture of two or more of them may alsobe used.

The ratio between the resin as the dispersed phase component and wateris preferably 60 to 400 parts by weight, more preferably 100 to 200parts by weight, of water based on 100 parts by weight of the resin.

When a resin emulsion is used as the thermoplastic resin, a conventionalresin emulsion may also be used. For example, resin emulsions described,for example, in Japanese Patent Publication No. 1426/1987, JapanesePatent Laid-Open Publication No. 56573/1991, Japanese Patent Laid-OpenPublication No. 79678/1991, Japanese Patent Laid-Open Publication No.160068/1991 or Japanese Patent Laid-Open Publication No. 18462/1992 assuch may be used. Commercially available resin emulsions may also beused. For example, Microgel E-1002 and Microgel E-5002 (styrene-acrylicresin emulsion; manufactured by Nippon Paint Co., Ltd.), Voncoat 4001(acrylic resin emulsion; manufactured by Dainippon Ink and Chemicals,Inc.), Voncoat 5454 (styrene-acrylic resin emulsion; manufactured byDainippon Ink and Chemicals, Inc.), SAE1014 (styrene-acrylic resinemulsion; manufactured by Zeon Corporation), or Saivinol SK-200 (acrylicresin emulsion; manufactured by Saiden Chemical Industry Co., Ltd.).

In the present invention, the thermoplastic resin may be mixed as a fineparticle powder with other ingredients in the water-based pigment inkcomposition. A method, however, is more preferably adopted in whichresin fine particles are dispersed in a water medium to prepare a resinemulsion which is then mixed with other ingredients in the inkcomposition. When the thermoplastic resin is used as a dispersant forthe pigment, mixing the thermoplastic resin in a pigment dispersionliquid form with other ingredients in the ink composition is preferred.

The thermoplastic resin is preferably contained in an amount of 0.1 to30% by weight, more preferably 0.3 to 15% by weight, in terms of solidcontent based on the total amount of the water-based pigment inkcomposition.

I-8-3. Water and Other Ingredients

The water-based pigment ink composition comprises water. The water maybe selected according to the description in the column of “I-4 Mainsolvent” in connection with the treatment liquid. Further, otheringredients in the water-based pigment ink composition may be properlyselected from conventional other ingredients such as penetrating agentsand humectants and according to the description, for example, thecolumns of “I-2. Surfactant”, “I-3. Low-surface tension organicsolvent”, “I-5. Other ingredients,” and “Wetting agent” which will bedescribed later.

The water-based pigment ink composition according to the presentinvention may be prepared by properly mixing the above ingredientsindividually or through the form of a pigment dispersion liquid or aresin emulsion in any desired sequence for dissolution (or dispersion)and then if necessary removing impurities and the like by filtration.

II. Primer Liquid for Printing

According to the second aspect of the present invention, there isprovided a primer liquid for printing for an ink jet recording mediumhaving a recording face formed of a plastic film.

As described above, the primer liquid for printing according to thepresent invention is used for printing on an ink jet recording mediumhaving a recording face formed of a plastic film. The primer liquidcomprises at least a heterocyclic ketone compound selected from thegroup consisting of cyclic ester compounds of formula (1), cyclic amidecompound of formula (2), and a combination thereof, a thermoplasticresin, and a main solvent, the thermoplastic resin being dispersed inthe primer liquid. In other words, the primer liquid according to thepresent invention comprises a dispersing medium comprising at least theheterocyclic ketone compound and the main solvent and the thermoplasticresin dispersed in the dispersing medium. As described below, the mainsolvent is preferably water. Preferably, the primer liquid according tothe present invention further comprises a surfactant and/or alow-surface tension organic solvent. More preferably, the primer liquidaccording to the present invention further comprises a surfactant orfurther comprises a surfactant and a low-surface tension organicsolvent. The primer liquid according to the present invention mayfurther comprise a wetting agent which will be described later.Preferably, the primer liquid according to the present invention iscoated onto the recording medium by an ink jet recording method.

The primer liquid according to the present invention is used forprinting on recording media having a recording face formed of a plasticfilm. The primer liquid according to the present invention can be usedfor printing on non-surface treated plastic films for ink jet printing,as well as surface-treated plastic films for ink jet printing.

The primer liquid according to the present invention is preferably usedwith the ink composition comprising the thermoplastic resin. In thiscase, the surface of the plastic film is strongly adhered to a resinfilm, formed by drying of the ink, through a primer film formed from theprimer liquid. As a result, a plastic recorded matter possessingexcellent rubbing resistance, scratch resistance, and waterfastness canbe formed. In this case, the ink composition is preferably a water-basedpigment ink composition comprising at least a pigment, a thermoplasticresin, and water. Therefore, in the present invention, since apigment-type water-based ink composition can be used, recorded matterspossessing excellent lightfastness can be formed on plastic films.

The primer film refers to such a state that water in the primer liquidhas been completely or partially evaporated to cure the thermoplasticresin contained in the primer liquid and consequently to bring the wholeprimer liquid to a unified film.

The reason for which the desired effect can be attained by the presentinvention is considered as follows. However, the following reason ishypothetical and should not be construed as limiting the presentinvention.

Upon coating onto a plastic film, the primer liquid according to thepresent invention is spread evenly on the surface of the plastic film.When water is evaporated in this state, the heterocyclic ketone compoundcan be allowed to stay homogeneously in a high concentration on thesurface of the plastic film. Consequently, it is considered that theheterocyclic ketone compound can bring a very shallow part from thesurface of the plastic film to a dissolved or wetted state. At the sametime, the resin component contained in the primer liquid is cured toallow the formation of a film to proceed and thus to form a primer film.In this case, the primer film together with dissolved plastic isconsidered to form a mixed layer. Accordingly, the plastic film surfaceis integrated with the resin film to provide a primer film stronglyadhered to the plastic film surface. An ink composition containing aresin, which can be brought to a film state upon heating, is depositedthereon, and the resin contained in the ink composition is then cured toform a film, whereby the cured film of this ink is bonded strongly tothe primer film. In this case, when the composition of the resincontained in the primer liquid is the same as the composition of theresin contained in the ink composition, the cured film of this ink isbonded more strongly to the primer film than the case where thecomposition of the resin contained in the primer liquid is differentfrom the composition of the resin contained in the ink composition. Theuse of the primer liquid is considered to significantly improve theadhesion between the ink layer and the plastic film through the primerfilm. The enhanced adhesion can substantially prevent the separation ofthe print caused, for example, by external force such as friction or theentry of water into the interface and thus can realize the formation ofplastic recorded matters possessing excellent rubbing resistance,scratch resistance and water resistance. Thus, the preparation of strongprinted matters utilizing the durability of the plastic film per se canbe realized.

In the primer liquid according to the present invention, preferably,since the heterocyclic ketone compound, which is a component capable ofdissolving the plastic, has been diluted with water, there issubstantially no possibility that the primer liquid breaks or damagesmembers constituting the printer with which the liquid comes intocontact. Further, since a preferred primer liquid according to thepresent invention is in an aqueous solution form, the primer liquid perse and vapor generated from the primer liquid are also highly safe.

II-1. Heterocyclic Ketone Compound

The primer liquid for printing according to the present inventioncomprises a heterocyclic ketone compound as an indispensable component.As described above, the heterocyclic ketone compound is a heterocyclicketone compound selected from the group consisting of cyclic estercompounds of formula (1), cyclic amide compounds of formula (2), and acombination thereof, preferably either a cyclic ester compound offormula (1) or a cyclic amide compound of formula (2).

Specifically, the heterocyclic ketone compound may be selected accordingto the description in the column of “I-1. Heterocyclic ketone compound”in the treatment liquid.

When the content of the cyclic ester compound in the primer liquidaccording to the present invention is excessively small in relation tothe whole primer liquid composition, the dissolution of the plasticsurface is unsatisfactory and, consequently, the primer film issometimes not adhered to the plastic. On the other hand, when thecontent of the cyclic ester compound is excessively large in relation tothe whole primer liquid composition, the dispersion stability of theresin component is sometimes deteriorated. In view of the above, thecontent of the cyclic ester compound in the primer liquid according tothe present invention is preferably selected so that the primer liquidcan be coated evenly onto the recording medium, has a predeterminedsurface tension, and does not substantially break or damage members,constituting a printer, in contact with the liquid. For example, thecontent of the cyclic ester compound is 0.1 to 40.0% by weight,preferably 2.0 to 25.0% by weight, based on the total amount of theprimer liquid.

In a preferred embodiment of the present invention, in the primer liquidfor printing, at least two cyclic amide compounds of formula (2) areused. When two or more cyclic amide compounds are used, the separationor crystallization of the cyclic amide compound in the course of theevaporation of the solvent from the primer liquid can be prevented.Further, the use of two or more cyclic amide compounds of formula (2)can enhance the solubility of the cyclic amide compounds in the primerliquid solvent and thus can prevent such an unfavorable phenomenon thatthe cyclic amide compounds are present unevenly on the plastic surfaceand, consequently, the plastic dissolution capability varies from partto part.

The content of the cyclic amide compound in the primer liquid accordingto the present invention is not particularly limited so far as theconcentration and surface tension of the primer liquid are suitable forcoating of the primer liquid evenly onto the recording medium by ink jetrecording and the primer liquid does not substantially break or damagemembers, constituting the printer, in contact with the liquid. Thecontent of the cyclic amide compound may be, for example, 0.1 to 40.0%by weight, preferably 2.0 to 25.0% by weight, based on the total amountof the primer liquid. When two or more cyclic amide compounds are used,the content of the cyclic amide compound refers to the total content ofthe two or more cyclic amide compounds.

In the primer liquid for printing, the content of the heterocyclicketone compound is, for example, 0.1 to 40.0% by weight, preferably 2.0to 25.0% by weight, based on the total amount of the primer liquid.

II-2. Thermoplastic Resin

The primer liquid according to the present invention comprises athermoplastic resin. Resins soluble or insoluble in the main solvent inthe primer liquid may be used as the thermoplastic resin. The aboveresin dispersant used in the dispersion of the pigment is suitable asthe resin soluble in the main solvent in the primer liquid. Regardingthe resin insoluble in the main solvent in the primer liquid,preferably, resin particles are added in a resin emulsion form to theprimer liquid. The resin emulsion comprises a main solvent as acontinuous phase and a resin component (a thermoplastic resin component)as a dispersed phase.

The thermoplastic resin used in the primer liquid according to thepresent invention may be specifically selected according to thedescription in the column of “I-8-2. Thermoplastic resin” in connectionwith the treatment liquid.

In the present invention, the thermoplastic resin may be mixed as a fineparticle powder with other ingredients in the primer liquid. However, amethod is preferably adopted in which the resin fine particles aredispersed in a water medium to prepare a resin emulsion which is thenmixed with other ingredients in the primer liquid.

From the viewpoints of the long-term storage stability and ejectionstability of the primer liquid, the particle diameter of the resin fineparticles preferred in the present invention is preferably in the rangeof 5 to 400 nm, more preferably in the range of 50 to 200 nm.

The content of the thermoplastic resin is preferably 0.1 to 15.0% byweight, more preferably 1.0 to 10.0% by weight, in terms of solidcontent based on the total amount of the primer liquid. In the primerliquid, when the content of the resin component is below the lower limitof the above defined content range, the primer film formed on theplastic surface is thin and, consequently, the adhesion between theprimer film and the ink layer is sometimes unsatisfactory. On the otherhand, when the content of the resin component is above the upper limitof the above defined content range, in some cases, the dispersion of theresin becomes unstable during the storage of the primer liquid, or evenupon the evaporation of a very small amount of water, the resincomponent is coagulated and solidified, making it impossible to form aneven primer film.

In a preferred embodiment of the present invention, the composition ofthe thermoplastic resin in the primer liquid component is the same asthe composition of the thermoplastic resin used in the water-basedpigment ink composition used in combination with the primer liquid(“II-10. Water-based pigment ink composition used in combination withprimer liquid”). When the thermoplastic resin in the primer liquidcomponent has the same composition as the thermoplastic resin used inthe water-based pigment ink composition, the affinity of the primer filmfor the resin film formed from the ink composition is enhanced and,consequently, the adhesion between the primer film and the resin filmcan be further enhanced.

II-3. Surfactant

The aqueous solution is usually repelled by plastics. Since, however, asurfactant and/or a low-surface tension organic solvent can be added tothe primer liquid according to the present invention, the heterocyclicketone compound can be coated evenly on the plastic surface. It isconsidered that, upon the evaporation of water from the evenly coatedprimer liquid, the heterocyclic ketone compound is fixed adequately onthe surface of the plastic and can dissolve the plastic surface only inits desired area. Further, when the primer liquid is evenly coated, theresin contained in the primer liquid can also be brought to an even filmon the plastic film surface.

The surfactant used in the primer liquid according to the presentinvention may be specifically selected according to the description inthe column of “I-2. Surfactant” in connection with the treatment liquid.

The content of the surfactant in the primer liquid according to thepresent invention is not particularly limited so far as the heterocyclicketone compound can be coated evenly on the plastic surface, and thesurfactant content may be properly selected depending upon the type ofthe surfactant used and the type and amount of the heterocyclic ketonecompound used. The content of the surfactant may be, for example, 0.01to 5.0% by weight, preferably 0.1 to 2.0% by weight, based on the totalamount of the primer liquid.

II-4. Low-Surface Tension Organic Solvent

In order to coat the heterocyclic ketone compound evenly on the plasticsurface, the primer liquid according to the present invention maycontain a low-surface tension organic solvent instead of or in additionto the surfactant.

The low-surface tension organic solvent used in the primer liquidaccording to the present invention may be specifically selectedaccording to the description in the column of “I-3. Low-surface tensionorganic solvent” in connection with the treatment liquid.

The content of the low-surface tension organic solvent in the primerliquid according to the present invention is not particularly limited,so far as the heterocyclic ketone compound can be evenly coated onto thesurface of plastic, and may be properly selected according to the kindand amount of the heterocyclic ketone compound and the surfactant used.

The content of the low-surface tension organic solvent may be, forexample, 0 to 25.0% by weight, preferably 2.0 to 15.0% by weight, basedon the total amount of the primer liquid.

Various properties of the primer liquid according to the presentinvention can be properly regulated. In a preferred embodiment of thepresent invention, the viscosity of the primer liquid is preferably notmore than 25 mPa·sec, more preferably not more than 10 mPa·sec (25° C.).When the viscosity is in this range, the primer liquid can be stablyejected through an ink ejection head. Further, the surface tension ofthe primer liquid according to the present invention can be properlyregulated and is preferably approximately in the range of 20.0 to 40.0mN/m (25° C.), more preferably approximately in the range of 25.0 to35.0 mN/m.

II-5. Wetting Agent

From the viewpoint of easiness on storage of the primer liquid and goodhandleability of the primer liquid in the coating, a conventionalwetting agent (a water soluble organic solvent) may be further added tothe primer liquid according to the present invention. The incorporationof the wetting agent can prevent coagulation and solidification of theresin component caused by the evaporation of water. Consequently, in inkjet coating, clogging of the ink jet head nozzle can be prevented, andejection stability can be ensured.

For example, water soluble polyhydric alcohols, particularly di- topentahydric alcohols having 2 to 10 carbon atoms, nitrogen-containinghydrocarbon solvents, for example, formamides, imidazolidinones,pyrrolidones, or amines, and sulfur-containing hydrocarbons may be usedas the wetting agent. They may used in a combination of two or more.

The water soluble polyhydric alcohol may be, for example, one of or acombination of two or more of di- or trihydric alcohols having 3 to 10carbon atoms, for example, glycerin, ethylene glycol, diethylene glycol,triethylene glycol, dipropylene glycol, hexylene glycol, and1,2,6-hexanetriol.

The content of the wetting agent may be, for example, 0 to 5.0% byweight, preferably 1.0 to 5.0% by weight, based on the total amount ofthe primer liquid. When the wetting agent content is in the abovedefined range, clogging preventive properties and ejection stability canbe ensured. When the wetting agent content is above the upper limit ofthe above defined range, drying is sometimes unsatisfactory.

II-6. Main Solvent

The primer liquid according to the present invention contains a mainsolvent. In order to coat a heterocyclic ketone compound-containingwater-soluble component thinly and evenly on the surface of plastic, inthe present invention, the heterocyclic ketone compound is diluted witha main solvent before coating. For example, water or a water-solubleorganic solvent is usable as the main solvent. In the present invention,water is preferred, for example, from the viewpoint of safety.

Accordingly, in the primer liquid according to the present invention,the main solvent is preferably water. Water may be pure water obtainedby ion exchange, ultrafiltration, reverse osmosis, distillation or thelike, or ultrapure water from the viewpoint of minimizing ionicimpurities. Water, which has been sterilized, for example, byultraviolet irradiation or by addition of hydrogen peroxide, issuitable, because this treatment can prevent the growth of mold orbacteria and, thus, the primer liquid can be stored for a long period oftime.

II-7. Other Ingredients

When the primer liquid according to the present invention contains theabove ingredients, a desired effect can be attained. If necessary, theprimer liquid may further comprise preservatives or fungicides, pHadjustors, dissolution aids, antioxidants, nozzle clogging preventiveagents and the like.

These other ingredients used in the primer liquid according to thepresent invention may be specifically selected according to thedescription in the column of “I-5. Other ingredients” in connection withthe treatment liquid.

II-8. Production of Primer Liquid

The primer liquid according to the present invention may be prepared byproperly mixing the above ingredients together in any order to dissolve(or disperse) them and if necessary removing impurities and the like byfiltration.

In the primer liquid according to the present invention, the mixingamounts of the above ingredients can be properly determined so as tosatisfy requirements, for example, that the heterocyclic ketone compoundcan be evenly coated onto the surface of plastic; the viscosity andsurface tension are such that the primer liquid can be ejected throughan ink jet recording head; the primer liquid is not coagulated orsolidified in a storage container or in nozzles in an ink jet head; andmembers in contact with liquids in an ink jet printer are not dissolvedin or broken by the primer liquid. For example, the primer liquidtypically has the following composition:

Heterocyclic ketone compound 0.1 to 40.0 wt % Thermoplastic resin 0.1 to15.0 wt % (solid basis) Surfactant 0.01 to 5.0 wt % Low-surface tensionorganic solvent   0 to 25.0 wt % Wetting agent   0 to 5.0 wt % WaterBalance.

Accordingly, in one preferred embodiment of the present invention, inthe primer liquid, the content of the heterocyclic ketone compound is0.1 to 40.0% by weight, the content of the thermoplastic resin is 0.1 to15.0% by weight in terms of solid content, and the content of thesurfactant is 0.01 to 5.0% by weight.

II-9. Recording Method Using Primer Liquid for Printing

As described above, the method for ink jet recording according to thesecond aspect of the present invention comprises coating a primer liquidfor printing onto a recording medium having a recording face formed of aplastic film to form a primer film, then ejecting droplets of an inkcomposition and depositing the droplets onto the recording face toperform printing.

In the step of coating a primer liquid, the primer liquid according tothe present invention is coated onto a recording medium in its recordingface. In this step, preferably, the primer liquid is previously coatedonto at least a part (a printing part) into which the ink is implantedin the next ink jet recording step. The coverage can be properlyregulated depending, for example, upon the state of the plastic film asthe recording medium and the type of the material of the plastic film,and the implantation amount of ink.

In the present invention, the primer liquid may be coated by any methodwithout particular limitation, and examples of coating methods includebrush coating, or contact-type coating using a conventional coatingdevice such as an air knife coater, a roll coater, a bar coater, a bladecoater, a slide hopper coater, a gravure coater, a flexogravure coater,a curtain coater, an extrusion coater, a floating knife coater, a Kommacoater, a die coater, gate roll coater, or a size press, andnon-contact-type coating using a spray, an ink jet head, a jet nozzle orthe like.

In the present invention, preferably, the primer liquid may be coated byan ink jet recording method in which droplets of the primer liquid areejected and deposited onto the recording medium in its recording face.When the ink jet recording method is adopted, the coating position andcoating amount of the primer liquid can be properly controlled. Theprimer liquid can be coated only onto the part to be printed bycontrolling the coating position. Accordingly, the amount of the primerliquid used can be saved, and, when the primer liquid is printed on theedge of the plastic recording medium, it is possible to prevent theprimer liquid from running over from the plastic recording medium. Whena large amount of solvent is coated onto the plastic recording medium,the whole plastic is dissolved or softened. However, the plasticrecording medium only in its very shallow part from the surface of theplastic recording medium can be selectively dissolved by controlling thecoating amount.

In a preferred embodiment of the present invention, the method for inkjet recording according to the second aspect of the present inventionfurther comprises, before the deposition of the ink composition, adrying step of evaporating water in the coated primer liquid to form aprimer film. After coating onto the recording medium, preferably, thewater in the primer liquid is almost or completely evaporated. Since theheterocyclic ketone compound contained in the primer liquid can also beevaporated by this drying operation, it is considered that the adhesionbetween the plastic recording medium and the formed primer film can alsobe enhanced.

After coating the primer liquid, drying for removing water can becarried out by a conventional method using conventional heat dryingmeans, for example, a conventional heating device such as an infraredheating device or a hot air heating device. In the present invention,preferably, drying treatment in the drying step can be carried out byheating with a heater or hot-air drying. Conditions for drying may beproperly varied depending, for example, upon the composition andcoverage of the primer liquid used. For example, in the case of heatingwith a heater or hot-air drying, the drying can be carried out at 25 to90° C. (preferably 40 to 70° C.) for one min to one day.

Next, in the ink jet recording method according to the second aspect ofthe present invention, after coating the primer liquid, an inkcomposition is deposited on the coating face. In this case, preferably,ink is deposited by an ink jet recording method. Further, the inkcomposition referred to herein is a water-based pigment ink compositioncomprising at least a pigment, a thermoplastic resin, and water whichwill be described later (“II-10. Water-based pigment ink compositionused in combination with primer liquid”).

In a preferred embodiment of the present invention, the ink jetrecording method according to the second aspect of the present inventionfurther comprises the step of heating the ink composition deposited onthe recording face to form a resin film. The heating means can becarried out by a conventional method using conventional heating means,for example, a conventional heating device such as an infrared heatingdevice or a hot air heating device. In the present invention,preferably, heating treatment in the heating step can be carried out byheating with a heater or hot-air drying. Conditions for heating is notlimited so far as the resin contained in the ink composition is cured byheating to form a resin film, and the heating conditions may be properlydetermined by taking into consideration, for example, the type of resinparticles. For example, in the case of heating with a heater or hot-airdrying, the heating can be carried out at 25 to 90° C. (preferably 40 to70° C.) for one min to one day (preferably 2 min to 16 hr).

II-10. Water-Based Pigment Ink Composition to be Used in Combinationwith Primer Liquid

The ink composition usable in the second aspect of the present inventionis preferably a water-based pigment ink composition comprising at leasta pigment, a thermoplastic resin, and water.

This water-based pigment ink composition may be the same as thewater-based pigment ink composition according to the first aspect of thepresent invention and may be properly selected and obtained according tothe description in the above column of “I-8. Water-based pigment inkcomposition to be used in combination with treatment liquid.”

III. Ink Composition

According to the third aspect of the present invention, there isprovided an ink composition for an ink jet recording medium having arecording face formed of a plastic film.

As described above, the ink composition according to the presentinvention comprises a heterocyclic ketone compound selected from thegroup consisting of cyclic ester compounds of formula (1), cyclic amidecompounds of formula (2), and a combination thereof, a thermoplasticresin, a colorant, and a main solvent, and the thermoplastic resin isdispersed in said ink composition. In other words, preferably, the inkcomposition according to the present invention comprises a dispersionmedium, comprising at least a heterocyclic ketone compound and a mainsolvent, and a thermoplastic resin dispersed in this dispersion medium(when the thermoplastic resin functions also as a dispersant for thepigment, the thermoplastic resin together with the pigment is dispersedin the dispersion medium). Preferably, the ink composition according tothe present invention further comprises a cyclic ether compound offormula (3). The colorant in the ink composition is preferably apigment. In this case, the pigment is in the state of being dispersed inthe ink composition. The main solvent is preferably water, as describedbelow. Further, preferably, the ink composition according to the presentinvention further comprises a surfactant and/or a low-surface tensionorganic solvent. More preferably, the ink composition according to thepresent invention further comprises a surfactant or further comprises asurfactant and a low-surface tension organic solvent. The inkcomposition according to the present invention may further comprise awetting agent

The ink composition according to the present invention is used with inkjet recording media of which the recording face is formed of a plasticfilm. Specifically, the ink composition according to the presentinvention is suitable for printing onto ink jet recording media of whichthe recording face is formed of a plastic film. More preferably, the inkcomposition according to the present invention is coated onto recordingmedia by ink jet recording.

The ink composition according to the present invention can also be usedfor printing onto all of plastic films for ink jet printing, notsubjected to surface treatment, and plastic films for ink jet printing,subjected to surface treatment.

When the ink composition according to the present invention is coatedonto recording medium having a recording face formed of a plastic film,a plastic recorded matter having good adhesion to the plastic film andexcellent waterfastness can be formed. The reason why the recordedmatter having excellent properties can be formed is as follows. However,it should be noted that the following explanation is hypothetical andshould not be construed as limiting the scope of the present invention.

The ink composition according to the present invention comprises asolvent, which can dissolve plastic constituting the recording face ofthe recording medium, and a resin which can be cured to form a film.Accordingly, upon the deposition of the ink composition onto the plasticfilm, the solvent dissolves the surface of the plastic film, and, at thesame time, upon water evaporation, the resin component in the inkcomposition is cured to form a film and thus to form an ink resin layer.Further, the plastic film surface can be strongly bonded to the resinfilm formed as a result of drying of the ink. Thus, it is consideredthat a plastic recorded matter having excellent adhesion to plasticfilms and excellent waterfastness can be formed.

A more detailed explanation will be given. When the ink compositionaccording to the present invention is coated onto the surface of aplastic film as a recording medium, the surface of the plastic film isbrought to a dissolved state due to the action of the solvent, capableof dissolving plastic, contained in the ink composition. In this case,when the content of the solvent capable of dissolving the plastic basedon the whole ink is excessively small, the dissolution of the plasticsurface is unsatisfactory and, consequently, in some cases, the resinfilm formed by drying of the ink is not adhered to the plastic surface.On the other hand, when the content of the solvent capable of dissolvingthe plastic is excessively large, in some cases, the whole plastic isdisadvantageously dissolved or softened by the solvent. For this reason,in the present invention, preferably, a heterocyclic ketone compoundhaving lower volatility and a cyclic ether compound having highervolatility are used as the solvent capable of dissolving the plastic.When these two compounds are used in combination, immediately afterprinting of the ink, due to both the compounds contained in the ink, theconcentration of the whole solvent capable of dissolving the plastic ishigh enough to dissolve the surface layer part on the surface of theplastic. Accordingly, the surface layer part of the plastic, which isless likely to be dissolved as compared with the inside of the plastic,can be dissolved. Thereafter, simultaneously with the evaporation ofwater in the ink, the highly volatile cyclic ether compound is alsoevaporated. On the other hand, in the ink in a semi-dried state, theheterocyclic ketone compound having lower volatility stays in the inkand continues to dissolve the surface of the plastic. Thus, indissolving the plastic film, at the time when the surface layer part isinitially dissolved, the concentration of the solvent can be increasedto a level that is high enough to dissolve the surface layer part. Afterthe dissolution of the surface layer part, the cyclic ether compoundhaving higher volatility is evaporated. Accordingly, the concentrationof the solvent can be reduced to a level that is suitable for dissolvingthe plastic part within the surface layer in the plastic. According tothis technique, it is possible to prevent an increase in theconcentration of the solvent capable of dissolving the plastic in itssurface to an unnecessarily high level. Therefore, excessive dissolutionof the plastic can be prevented, and the dissolved state can be limitedonly to a very shallow part in the surface of the plastic.

While the very shallow part in the plastic surface is dissolved, uponthe evaporation of water in the ink composition on the plastic, thethermoplastic resin contained in the ink composition forms a resin film.In this case, when the plastic surface is in a properly dissolved state,the resin to be brought to a film together with the plastic surface canform a mixed layer. Further, as drying of the ink composition proceeds,the solvent capable of dissolving the plastic is completely evaporatedand, further, the ink composition can be fully brought to a film state.The recorded matter thus formed is considered to have a structure of“(plastic film surface)/(mixed layer composed of plastic and inkresin)/(resin layer of ink composition).” In the mixed layer, theplastic is integral with the film formed as a result of curing of theresin contained in the ink. Accordingly, it is considered that theadhesion between the plastic film and the ink composition film is moresignificantly improved than the case where the ink resin layer is indirect contact with the plastic layer. The enhanced adhesion cansubstantially prevent the separation of the print caused, for example,by external force such as friction or the entry of water into theinterface and thus can realize the formation of plastic recorded matterspossessing excellent rubbing/scratch resistance, and water resistance.Thus, the preparation of strong printed matters utilizing the durabilityof the plastic film per se can be realized.

In the ink composition according to the present invention, preferably,since the heterocyclic ketone compound, which is a component capable ofdissolving the plastic, and preferably further the cyclic ether compoundhave been diluted with water, there is substantially no possibility thatthe ink composition breaks or damages members constituting the printerwith which the liquid comes into contact. Further, since the inkcomposition according to the present invention is typically in anaqueous solution form, the ink composition per se and vapor generatedfrom the ink composition are also highly safe. Furthermore, since theink composition according to the present invention may be a pigment-typewater-based ink composition using a pigment as a colorant, recordedmatter having excellent lightfastness can be formed on plastic films.

III-1. Heterocyclic Ketone Compound

The ink composition for printing according to the present inventioncomprises a heterocyclic ketone compound as an indispensable component.As described above, the heterocyclic ketone compound is a heterocyclicketone compound selected from the group consisting of cyclic estercompounds of formula (1), cyclic amide compounds of formula (2), and acombination thereof, preferably either a cyclic ester compound offormula (1) or a cyclic amide compound of formula (2).

Specifically, the heterocyclic ketone compound may be selected accordingto the description in the column of “I-1. Heterocyclic ketone compound”in the treatment liquid.

When the content of the cyclic ester compound in the ink compositionaccording to the present invention is excessively small in relation tothe whole ink composition, the dissolution of the plastic surface isunsatisfactory and, consequently, the film derived from the inkcomposition is not sometimes adhered to the plastic. On the other hand,when the content of the cyclic ester compound is excessively large inrelation to the whole ink composition, the dispersion stability of theresin component in the ink is sometimes deteriorated. In view of theabove, the content of the cyclic ester compound in the ink compositionaccording to the present invention is preferably selected so that theink composition can be coated evenly onto the recording medium, has apredetermined surface tension, and does not substantially break ordamage members, constituting a printer, in contact with the liquid.Further, the amount of the cyclic ether compound used in combinationwith the heterocyclic ketone compound should also be taken intoconsideration. For example, the content of the cyclic ester compound is0.1 to 10.0% by weight, preferably 1.0 to 8.0% by weight, based on thetotal amount of the ink composition.

In a preferred embodiment of the present invention, in the inkcomposition, at least two cyclic amide compounds of formula (2) areused. When two or more cyclic amide compounds are used, the separationor crystallization of the cyclic amide compound in the course of theevaporation of the solvent from the ink composition can be prevented.Further, the use of two or more cyclic amide compounds of formula (2)can enhance the solubility of the cyclic amide compounds in the inkcomposition solvent and thus can prevent such an unfavorable phenomenonthat the cyclic amide compounds are present unevenly on the plasticsurface and, consequently, the plastic dissolution capability variesfrom part to part.

When the content of the cyclic amide compound in the ink compositionaccording to the present invention is excessively small in relation tothe whole ink composition, the dissolution of the plastic surface isunsatisfactory and, consequently, the film derived from the inkcomposition is not sometimes adhered to the plastic. On the other hand,when the content of the cyclic amide compound is excessively large inrelation to the whole ink composition, the dispersion stability of theresin component in the ink is sometimes deteriorated. In view of theabove, the content of the cyclic amide compound in the ink compositionaccording to the present invention is preferably selected so that theink composition can be coated evenly onto the recording medium, has apredetermined surface tension, and does not substantially break ordamage members, constituting a printer, in contact with the liquid.Further, the amount of the cyclic ether compound used in combinationwith the heterocyclic ketone compound should also be taken intoconsideration. For example, the content of the cyclic amide compound is0.1 to 20.0% by weight, preferably 1.0 to 10.0% by weight, based on thetotal amount of the ink composition. When two or more cyclic amidecompounds are used, the content refers to the total content of the twoor more compounds.

Accordingly, in the ink composition, the content of the heterocyclicketone compound is, for example, 0.1 to 10.0% by weight, preferably 0.1to 20.0% by weight, more preferably 1.0 to 10.0% by weight, still morepreferably 1.0 to 8.0% by weight, based on the total amount of the inkcomposition.

III-2. Cyclic Ether Compound

Preferably, the ink composition according to the present inventionfurther comprises a cyclic ether compound of formula (3).

In formula (3), as described above, R′ represents a straight chain orbranched chain C2 to C12 saturated hydrocarbon chain, or a straightchain or branched chain C2 to C12 saturated ether chain. Here, forexample, “C2 to C12” in “C2 to C12 saturated hydrocarbon chain” meansthat the number of carbon atoms in the saturated hydrocarbon chain is 2to 12. This is true of a saturated ether chain.

When R′ represents a saturated hydrocarbon chain, the number of carbonatoms is preferably C2 to C8, more preferably C2 to 6, still morepreferably C2 to C5, still more preferably C3 to C5. The definition ofthe straight or branched saturated hydrocarbon chain is the same as thedefinition in the above heterocyclic ketone compound. Specific examplesof saturated hydrocarbon chains in R′ include straight C4 saturatedhydrocarbon chains.

The straight chain or branched chain C2 to C12 saturated ether chainrefers to a chain comprising at least one ether bond inserted into anycarbon-carbon bond in the above straight chain or branched chain C2 toC12 saturated hydrocarbon chain. Preferably, only one ether bond iscontained in the saturated ether chain. For example, the straightsaturated ether chain is preferably represented by —(CH₂)q—O—(CH₂)r-wherein q+r is an integer of 2 to 12. The straight or branched saturatedether chain may if necessary be further substituted, for example, by ahydroxyl group or hydroxymethylene.

Specific examples of cyclic ether compounds include oxirane,oxacyclobutane (oxetane), tetrahydrofuran (oxolane), 3-methyl-oxolane,oxane, 1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, 2-methyltetrahydrofuran,and 1,3,5-trioxane. The cyclic ether compound is preferably selectedfrom the group consisting of tetrahydrofuran, 1,4-dioxane, and2-methyltetrahydrofuran. More preferred are tetrahydrofuran and1,4-dioxane.

These cyclic ether compounds may be used as a mixture of two or more.

The cyclic ether compound used in the present invention may if necessarybe synthesized or alternatively may be a commercially available product.

When the content of the cyclic ether compound based on the whole inkcomposition is excessively low, the dissolution of the plastic surfaceis unsatisfactory. In this case, the film formed from the inkcomposition is not sometimes adhered to the plastic. On the other hand,when the content of the cyclic ether compound is excessively high, thedispersion stability of the resin component in the ink is sometimesdeteriorated. Accordingly, while taking the above points intoconsideration, the content of the cyclic ether compound is preferablyselected so that members, constituting a printer, in contact with theliquid are hardly broken or damaged. In determining the content of thecyclic ether compound, preferably the amount of the heterocyclic ketonecompound used in combination with the cyclic ether compound is alsotaken into consideration. The content of the cyclic ether compound is,for example, 0.1 to 10.0% by weight, preferably 0.5 to 5.0% by weight,based on the total amount of the ink composition.

In a preferred embodiment of the present invention, preferredcombinations of cyclic ester compound with cyclic ether compoundsinclude:

a combination of γ-butyrolactone with tetrahydrofuran;

a combination of γ-butyrolactone with 1,4-dioxane; a combination ofγ-butyrolactone with 2-methyltetrahydrofuran;

a combination of propylene carbonate with tetrahydrofuran;

a combination of propylene carbonate with 1,4-dioxane; and

a combination of propylene carbonate with 2-methyltetrahydrofuran.

In a preferred embodiment of the present invention, preferredcombinations of cyclic amide compounds with cyclic ether compoundsinclude:

a combination of 2-pyrrolidone with ε-caprolactam and tetrahydrofuran;

a combination of 2-pyrrolidone with ε-caprolactam and 1,4-dioxane;

a combination of 2-pyrrolidone with ε-caprolactam and2-methyltetrahydrofuran;

a combination of N-methyl-2-pyrrolidone with ε-caprolactam andtetrahydrofuran;

a combination of N-methyl-2-pyrrolidone with ε-caprolactam and1,4-dioxane; and

a combination of N-methyl-2-pyrrolidone with ε-caprolactam and2-methyltetrahydrofuran.

III-3. Thermoplastic Resin

The ink composition according to the present invention comprises athermoplastic resin. The thermoplastic resin is in the state of beingdispersed in the ink composition. The thermoplastic resin may be solubleor insoluble in the water-based ink medium. The above-described resindispersant used in the dispersion of the pigment is suitable as theresin soluble in the water-based ink medium. Regarding the resininsoluble in the water-based ink medium, preferably, resin particles areadded in the form of a resin emulsion to the ink composition The resinemulsion comprises water as a continuous phase and a resin component (athermoplastic resin component) as a dispersed phase.

The thermoplastic resin used in the ink composition according to thepresent invention may be specifically selected according to thedescription in the column of “I-8-2. Thermoplastic resin” in connectionwith the treatment liquid.

In the present invention, the thermoplastic resin may be mixed as a fineparticle powder with other ingredients in the ink composition. However,a method is preferably adopted in which the resin fine particles aredispersed in a water medium to prepare a resin emulsion which is thenmixed with other ingredients in the ink composition.

From the viewpoints of the long-term storage stability and ejectionstability of the ink composition, the particle diameter of the resinfine particles preferred in the present invention is preferably in therange of 5 to 400 nm, more preferably in the range of 50 to 200 nm.

The content of the thermoplastic resin is preferably 0.1 to 15.0% byweight, more preferably 0.5 to 10.0% by weight, in terms of solidcontent based on the total amount of the ink composition. In the inkcomposition, when the content of the resin component is below the lowerlimit of the above defined content range, the ink film formed on theplastic surface is thin and, consequently, the adhesion between the inkcomposition and the plastic surface is sometimes unsatisfactory. On theother hand, when the content of the resin component is above the upperlimit of the above defined content range, in some cases, the dispersionof the resin becomes unstable during the storage of the ink composition,or even upon the evaporation of a very small amount of water, the resincomponent is coagulated and solidified, making it impossible to form aneven film.

III-4. Colorant

The ink composition according to the present invention comprises acolorant. Colorants usable herein include dyes or pigments. In thepresent invention, the colorant is preferably a pigment.

The type of the dye is not particularly limited, and acid dyes, directdyes, reactive dyes, and basic dyes are usable.

When the pigment is used as the colorant, the ink composition accordingto the present invention may contain any pigment which has hitherto beenused in water-based ink compositions for ink jet recording. For example,organic pigments or inorganic pigments, which have hitherto been used inink compositions for ink jet recording, can be used as the pigment. Thepigment may be added, to the ink composition, as a resin dispersedpigment obtained by dispersing the pigment together with a dispersantsuch as a water soluble resin or a surfactant, or as a surface treatmentpigment obtained by introducing a hydrophilic group into the surface ofa pigment to render the pigment dispersible or dissolvable in an aqueousmedium without the aid of any dispersant. When the pigment is dispersedwith the aid of a resin dispersant, the above thermoplastic resin may beused as the dispersant. Further, two or more pigments may be used incombination.

The pigment used in the ink composition according to the presentinvention may be specifically selected according to the description inthe column of “I-8-1. Pigment” in connection with the treatment liquid.

The content of the pigment is preferably 0.5 to 15% by weight, morepreferably 1.0 to 10.0% by weight, based on the whole ink composition.

III-5. Surfactant

The ink composition according to the present invention preferablycomprises a surfactant and/or a low-surface tension organic solvent. Theaqueous solution is usually repelled by plastics. However, when asurfactant and/or a low-surface tension organic solvent is added to theaqueous solution, the aqueous solution, that is, the ink composition,can be coated evenly on the plastic surface. It is considered that, uponthe evaporation of water from the evenly coated ink composition, theheterocyclic ketone compound and the like are fixed adequately on thesurface of the plastic and can dissolve the plastic surface only in itsdesired area. Further, when the ink composition is evenly coated, theresin contained in the ink composition can also be brought to an evenfilm on the plastic film surface.

The surfactant used in the ink composition according to the presentinvention may be specifically selected according to the description inthe column of “I-2. Surfactant” in connection with the treatment liquid.

The content of the surfactant in the ink composition is not particularlylimited so far as the ink composition can be coated evenly on theplastic surface, and the surfactant content may be properly selecteddepending upon the type of the surfactant used and the type and amountof other ingredients constituting the ink composition. The content ofthe surfactant may be, for example, 0.01 to 5.0% by weight, preferably1.0 to 2.0% by weight, based on the total amount of the ink composition.

III-6. Low-Surface Tension Organic Solvent

In order to coat the heterocyclic ketone compound and the cyclic ethercompound evenly on the plastic surface, the ink composition according tothe present invention may contain a low-surface tension organic solventinstead of or in addition to the surfactant.

The low-surface tension organic solvent used in the ink compositionaccording to the present invention may be specifically selectedaccording to the description in the column of “I-3. Low-surface tensionorganic solvent” in connection with the treatment liquid.

The content of the low-surface tension organic solvent in the inkcomposition according to the present invention is not particularlylimited, so far as the cyclic ketone compound and the like can be evenlycoated onto the surface of plastic, and may be properly selectedaccording to the kind and amount of the heterocyclic ketone compound,cyclic ether compound and the surfactant used. The content of thelow-surface tension organic solvent may be, for example, 0 to 10.0% byweight, preferably 2.0 to 8.0% by weight, based on the total amount ofthe ink composition.

Various properties of the ink composition according to the presentinvention can be properly regulated. In a preferred embodiment of thepresent invention, the viscosity of the ink composition is preferablynot more than 25 mPa·sec, more preferably not more than 10 mPa·sec (25°C.). When the viscosity is in this range, the ink composition can bestably ejected through an ink ejection head. Further, the surfacetension of the ink composition according to the present invention can beproperly regulated and is preferably approximately in the range of 20.0to 40.0 mN/m (25° C.), more preferably approximately in the range of25.0 to 35.0 mN/m.

III-7. Wetting Agent

From the viewpoint of easiness on storage of the ink composition andgood handleability of the ink composition in the coating, a conventionalwetting agent (a water soluble organic solvent) may be further added tothe ink composition according to the present invention. Theincorporation of the wetting agent can prevent coagulation andsolidification of the resin component caused by the evaporation ofwater. Consequently, in ink jet coating, clogging of the ink jet headnozzle can be prevented, and ejection stability can be ensured.

The wetting agent used in the ink composition according to the presentinvention may be specifically selected according to the description inthe column of “II5. Wetting agent” in connection with the treatmentliquid.

The content of the wetting agent may be, for example, 0 to 20.0% byweight, preferably 1.0 to 10.0% by weight, based on the total amount ofthe ink composition. When the wetting agent content is in the abovedefined range, clogging preventive properties and ejection stability canbe ensured. When the wetting agent content is above the upper limit ofthe above defined range, drying is sometimes unsatisfactory.

III-8. Main Solvent

The ink composition according to the present invention contains a mainsolvent. In order to coat a water soluble organic solvent containing aheterocyclic ketone compound and optionally a cyclic ether compoundthinly and evenly on the surface of plastic, in the present invention,the heterocyclic ketone compound and the like are diluted with a mainsolvent before coating. For example, water or a water-soluble organicsolvent is usable as the main solvent. In the present invention, wateris preferred, for example, from the viewpoint of safety.

Accordingly, in the ink composition according to the present invention,the main solvent is preferably water. Water may be pure water obtainedby ion exchange, ultrafiltration, reverse osmosis, distillation or thelike, or ultrapure water from the viewpoint of minimizing ionicimpurities. Water, which has been sterilized, for example, byultraviolet irradiation or by addition of hydrogen peroxide, issuitable, because this treatment can prevent the growth of mold orbacteria and, thus, the ink composition can be stored for a long periodof time.

III-9. Other Ingredients

When the ink composition according to the present invention contains theabove ingredients, a desired effect can be attained. If necessary, theink composition may further comprise preservatives or fungicides, pHadjustors, dissolution aids, antioxidants, nozzle clogging preventiveagents and the like

These other ingredients used in the ink composition according to thepresent invention may be specifically selected according to thedescription in the column of “I-5. Other ingredients” in connection withthe treatment liquid.

III-10. Production of Ink Composition

The ink composition according to the present invention may be preparedby properly mixing, in any order, the above ingredients individually, orthrough the form of a pigment dispersant or resin emulsion fordissolution or dispersion, and optionally filtering the solution ordispersion liquid to remove impurities.

In the ink composition according to the present invention, the mixingamounts of the above ingredients can be properly determined so as tosatisfy requirements, for example, that the heterocyclic ketone compoundand the cyclic ether compound are used in such an amount that the inkcomposition can dissolve the surface of the plastic; the viscosity andsurface tension are such that the ink composition can be ejected throughan ink jet recording head; the ink composition is not coagulated orsolidified in a storage container or in nozzles in an ink jet head; andmembers in contact with liquids in an ink jet printer are not dissolvedin or broken by the ink composition. For example, the ink compositiontypically has the following composition:

Cyclic ester compound 0.1 to 10.0% by weight; Cyclic ether compound 0.1to 10.0% by weight; Thermoplastic resin 0.1 to 15.0% by weight  (solidcontent); Pigment 0.5 to 15.0% by weight; Surfactant 0.01 to 5.0% byweight; Low-surface tension   0 to 10.0% by weight; organic solventWetting agent and   0 to 20.0% by weight; Water Balance.

The following composition may be mentioned as another example of the inkcomposition.

Cyclic amide compound 0.1 to 20.0% by weight; Cyclic ether compound 0.1to 10.0% by weight; Thermoplastic resin 0.1 to 15.0% by weight  (solidcontent); Pigment 0.5 to 15.0% by weight; Surfactant 0.01 to 5.0% byweight; Low-surface tension   0 to 10.0% by weight; organic solventWetting agent and   0 to 20.0% by weight; Water Balance.

Accordingly, in one preferred embodiment of the present invention, inthe ink composition, the content of the cyclic ester compound is 0.1 to10.0% by weight, the content of the cyclic ether compound is 0.1 to10.0% by weight in terms of solid content, and the content of thethermoplastic resin is 0.1 to 15.0% by weight in terms of solid content.

Accordingly, in another preferred embodiment of the present invention,in the ink composition, the content of the cyclic amide compound is 0.1to 20.0% by weight, the content of the cyclic ether compound is 0.1 to10.0% by weight in terms of solid content, and the content of thethermoplastic resin is 0.1 to 15.0% by weight in terms of solid content.

III-10. Recording Method Using Ink Composition According to the PresentInvention

As described above, the ink jet recording method according to the thirdaspect of the present invention comprises ejecting and depositingdroplets of an ink composition onto a recording medium having arecording face formed of a plastic film to perform printing. In the inkcomposition according to the present invention, the amount of theingredient capable of dissolving the plastic film is regulated dependingupon the state of the plastic film as the recording medium and the typeof the material for the plastic film and on ink drying conditions.Accordingly, the coverage of the ink can be properly varied dependingupon the reproducibility of the image.

In a preferred embodiment of the present invention, the method for inkjet recording according to the third aspect of the present inventionfurther comprises the step of heating the ink composition deposited onthe recording face to form a resin film. It is considered that, in thecourse of this operation, the heterocyclic ketone compound and cyclicether compound contained in the ink composition can be evaporated, and,thus, the adhesion between the plastic and the formed resin film canalso be further improved. In this case, the heating may be carried outby conventional heating means, for example, a conventional heatingdevice such as an infrared heating device or a hot air heating deviceaccording to a conventional method. In the present invention,preferably, the heat treatment in the heating step is carried out byheating with a heater or by warm air drying. Heating conditions are notparticularly limited, so far as the resin contained in the inkcomposition can be cured upon heating to form a resin film, and may beproperly determined by taking into consideration, for example, the typeof resin particles. For example, in the case of heating with a heater orwarm air drying, heating may be carried out at 25 to 90° C., preferably40 to 70° C., for one min to one day, preferably 3 min to 18 hr.

According to another aspect of the present invention, there is provideda printed matter printed by a method for ink jet recording according tothe present invention.

In a further aspect of the present invention, there is provided use of acyclic ester compound of formula (1) according to claim 1 or a cyclicamide compound of formula (2), in the production of a treatment liquid,a primer liquid for printing, or an ink composition for use in an inkjet recording medium having a recording face of a plastic film.

EXAMPLES

The present invention is further illustrated by the following Examplesthat are not intended as a limitation of the invention.

a. Treatment Liquid (Cyclic Ester Compound)

A-1. Preparation of Treatment Liquids

Treatment liquids according to the present invention were preparedaccording to the following formulations.

Treatment Liquid 1e:

γ-Butyrolactone 10.0% by weight  Diethylene glycol monobutyl ether 3.0%by weight Surfynol 465 1.0% by weight Pure water Balance

Treatment Liquid 2e:

Propylene carbonate 15.0% by weight  Diethylene glycol monobutyl ether3.0% by weight Surfynol 465 1.0% by weight Pure water Balance

A-2. Preparation of Water-Based Pigment Ink Compositions

Water-based pigment ink compositions were prepared according to thefollowing formulation.

Black Ink:

Carbon Black MA7 (manufactured by 5.0% by weight Mitsubishi Kasei Corp.)Styrene-acrylic acid copolymer 2.5% by weight (thermoplastic resin)(solid basis) Glycerin 3.0% by weight Diethylene glycol 4.0% by weightDiethylene glycol monobutyl ether 3.0% by weight 2-pyrrolidone 3.0% byweight Surfynol 465 1.0% by weight Pure water Balance

Cyan Ink:

C.I. Pigment Blue 15:3 2.0% by weight Styrene-acrylic acid copolymer1.0% by weight (thermoplastic resin) (solid basis) Glycerin 3.0% byweight Diethylene glycol 6.0% by weight Diethylene glycol monobutylether 3.0% by weight 2-Pyrrolidone 3.0% by weight Surfynol 465 1.0% byweight Pure water Balance

Magenta Ink:

C.I. Pigment Red 122 3.0% by weight Styrene-acrylic acid copolymer 1.5%by weight (thermoplastic resin) (solid basis) Glycerin 3.0% by weightDiethylene glycol 5.0% by weight Diethylene glycol monobutyl ether 3.0%by weight 2-Pyrrolidone 3.0% by weight Surfynol 465 1.0% by weight Purewater Balance

Yellow Ink:

C.I. Pigment Yellow 74 2.0% by weight Styrene-acrylic acid copolymer1.0% by weight (thermoplastic resin) (solid basis) Glycerin 3.0% byweight Diethylene glycol 6.0% by weight Diethylene glycol monobutylether 3.0% by weight 2-Pyrrolidone 3.0% by weight Surfynol 465 1.0% byweight Pure water Balance

A-3. Evaluation Test

Preparation of Printing Samples Examples A1 to A5

Treatment liquid 1e or treatment liquid 2e was coated at 50% duty onto anon-surface-treated flexible vinyl chloride film (Scotchcal Film,manufactured by Sumitomo 3M Ltd.) for ink jet printing, with an ink jetprinter (TM-J8000; manufactured by Seiko Epson Corporation). Thereafter,the coated film was dried until the water was removed by evaporation ina thermostatic chamber kept at a temperature of 60° C. and a relativehumidity of 20% for one min. Immediately after that, a 100% duty patternwas printed with an ink jet printer (TM-J8000; manufactured by SeikoEpson Corporation) loaded with a black ink or with a cyan ink, a magentaink, and a yellow ink.

Printing samples were dried in a thermostatic chamber kept at atemperature of 60° C. and a relative humidity of 20% for one hr andfurther at room temperature for one day and were then subjected to thefollowing evaluation tests.

Preparation of Printing Samples Examples A6 to A9 (Comparative Examples)

Printing was performed at 100% duty on the flexible vinyl chloride film(not coated with the treatment liquid) as described in Example A1 withan ink jet printer (TM-J8000; manufactured by Seiko Epson Corporation)loaded with a black ink or with a cyan ink, a magenta ink, and a yellowink. The printed matters thus obtained were dried at a temperature of60° C. and a relative humidity 20% in a thermostatic chamber for one hrand further at room temperature for one day and were then subjected tothe following evaluation tests.

Evaluation of Samples

Evaluation 1: Rubbing Resistance and Scratch Resistance

The sample was subjected to a pencil test with pencils having respectivehardnesses by a 750 g-load pencil scratch tester (manufactured by ImotoMachinary Co., Ltd.) specified in JIS K 5600-5-4 and was then inspectedfor the removal of the printed film, that is, scratch damage (cohesivefailure). The results were evaluated according to the followingcriteria.

A: Upon a scratch test with a pencil having hardness HB, no scratchdamage was observed, and the primer coating film was not exposed.

B: Upon a scratch test with a pencil having hardness HB, scratch damageon such a level that the primer coating film was exposed, was observed,whereas, upon a scratch test with a pencil having hardness B, no scratchdamage was observed, and the primer coating film was not exposed.

C: Upon a scratch test with a pencil having hardness B, scratch damageon such a level that the primer coating film was exposed, was observed.

Evaluation 2: Adhesion

A pressure-sensitive adhesive tape (Cello-Tape No. 252; manufactured bySekisui Chemical Co., Ltd.) was applied to the printing sample in itsprinted part and was rubbed twice or thrice with a finger. Thereafter,the pressure-sensitive adhesive tape was separated from the printingsample. The rubbed printed part was visually inspected. The results wereevaluated according to the following criteria.

A: No separation of the ink (colorant) from the vinyl chloride film.

B: Partial separation of the ink (colorant) from the vinyl chloridefilm.

C: Complete separation of the ink (colorant) from the vinyl chloridefilm.

Evaluation 3: Waterfastness

One drop of tap water was deposited on the printing sample in itsprinted part, and the sample was allowed to stand for one min. The waterdroplet was wiped off with gauze. After the wiping-off of the waterdroplet, the state of the printed part and the state of the gauze werevisually inspected. The results were evaluated according to thefollowing criteria.

A: The ink (colorant) was not separated from the vinyl chloride film atall, and no coloration of the gauze was observed.

B: A part of the ink (colorant) was separated from the vinyl chloridefilm, and coloration of the gauze was observed.

C: The ink (colorant) was completely separated from the vinyl chloridefilm, and coloration of the gauze was observed.

The results were as shown in Table 1 below.

TABLE 1 Water-based Eval- Eval- Eval- Treatment pigment ink uationuation uation liquid composition 1 2 3 Example A1 Treatment Black ink AA A liquid 1e Example A2 Treatment Black ink A A A liquid 2e Example A3Treatment Cyan ink A A A liquid 1e Example A4 Treatment Magenta ink A AA liquid 1e Example A5 Treatment Yellow ink A A A liquid 1e Example A6None Black ink C B C (comparative) Example A7 None Cyan ink A B B(comparative) Example A8 None Magenta ink B B C (comparative) Example A9None Yellow ink B C C (comparative)

B. Treatment Liquid (Cyclic Amide Compound)

B-1. Preparation of Treatment Liquids

Treatment liquids according to the present invention were preparedaccording to the following formulations.

Treatment Liquid 1a:

2-Pyrrolidone 10.0% by weight ε-Caprolactam 15.0% by weight Diethyleneglycol monobutyl ether  3.0% by weight Surfynol 465  1.0% by weight Purewater Balance

Treatment Liquid 2a:

N-Methyl-2-pyrrolidone 10.0% by weight ε-Caprolactam 15.0% by weightDiethylene glycol monobutyl ether  3.0% by weight Surfynol 465  1.0% byweight Pure water Balance

B-2. Preparation of Water-Based Pigment Ink Compositions

Water-based pigment ink compositions were prepared according to theformulations as described in A-2.

B-3. Evaluation Test

Preparation of Printing Samples Examples B1 to B5

Treatment liquid 1e or treatment liquid 2e was coated at 50% duty onto anon-surface-treated specialty flexible vinyl chloride film (ScotchcalFilm, manufactured by Sumitomo 3M Ltd.) for ink jet printing, with anink jet printer (TM-J8000; manufactured by Seiko Epson Corporation).Thereafter, the coated film was dried until the water was removed byevaporation in a thermostatic chamber kept at a temperature of 60° C.and a relative humidity of 20% for 5 min. Immediately after that, a 100%duty pattern was printed with an ink jet printer (TM-J8000; manufacturedby Seiko Epson Corporation) loaded with a black ink or with a cyan ink,a magenta ink, and a yellow ink.

Printing samples were dried in a thermostatic chamber kept at atemperature of 60° C. and a relative humidity of 20% for one hr andfurther at room temperature for one day and were then subjected to thefollowing evaluation tests.

Preparation of Printing Samples Examples B6 to B9 (Comparative Examples)

Printing samples of Examples B6 to B9 were prepared in the same manneras in Examples A6 to A9. The printing samples were dried in athermostatic chamber kept at a temperature of 60° C. and a relativehumidity of 20% for one hr and further at room temperature for one dayand were then subjected to the following evaluation tests.

Evaluation of Samples

The samples were evaluated in the same manner as in evaluations 1 to 3in A-3 above.

The results were as shown in Table 2 below.

TABLE 2 Water-based Eval- Eval- Eval- Treatment pigment ink uationuation uation liquid composition 1 2 3 Example B1 Treatment Black ink AA A liquid 1a Example B2 Treatment Black ink A A A liquid 2a Example B3Treatment Cyan ink A A A liquid 1a Example B4 Treatment Magenta ink A AA liquid la Example B5 Treatment Yellow ink A A A liquid 1a Example B6None Black ink C B C (comparative) Example B7 None Cyan ink A B B(comparative) Example B8 None Magenta ink B B C (comparative) Example B9None Yellow ink B C C (comparative)

C. Primer Liquid (Cyclic Ester Compound)

C-1. Preparation of Primer Liquids

Primer liquids according to the present invention were preparedaccording to the following formulations.

Primer Liquid 1e:

γ-Butyrolactone 5.0% by weight Styrene-acrylic acid copolymer 5.0% byweight (solid basis) Diethylene glycol 4.0% by weight Diethylene glycolmonobutyl ether 3.0% by weight Surfynol 465 1.0% by weight Pure waterBalance

Primer Liquid 2e:

Propylene carbonate 5.0% by weight Styrene-acrylic acid copolymer 5.0%by weight (solid basis) Diethylene glycol 4.0% by weight Diethyleneglycol monobutyl ether 3.0% by weight Surfynol 465 1.0% by weight Purewater Balance

C-2. Preparation of Water-Based Pigment Ink Compositions

Water-based pigment ink compositions were prepared according to theformulations as described in A-2.

C-3. Evaluation Test

Preparation of Printing Samples Examples C1 to C5

Primer liquid 1e or primer liquid 2e was coated at 50% duty onto anon-surface-treated specialty flexible vinyl chloride film (ScotchcalFilm, manufactured by Sumitomo 3M Ltd.) for ink jet printing, with anink jet printer (TM-J8000; manufactured by Seiko Epson Corporation).Thereafter, the coated film was dried in a thermostatic chamber kept ata temperature of 60° C. and a relative humidity of 20% for one hr toform a primer film. A 100% duty pattern was then printed with an ink jetprinter (TM-J8000; manufactured by Seiko Epson Corporation) loaded witha black ink or with a cyan ink, a magenta ink, and a yellow ink.

Printing samples were dried in a thermostatic chamber kept at atemperature of 60° C. and a relative humidity of 20% for one hr andfurther at room temperature for one day and were then subjected to thefollowing evaluation tests.

Preparation of Printing Samples Examples C6 to C9 (Comparative Examples)

Printing was performed at 100% duty on the flexible vinyl chloride film(not coated with the primer liquid) as described in Example C1 with anink jet printer (TM-J8000; manufactured by Seiko Epson Corporation)loaded with a black ink or with a cyan ink, a magenta ink, and a yellowink. The printed matters thus obtained were dried at a temperature of60° C. and a relative humidity 20% in a thermostatic chamber for one hrand further at room temperature for one day and were then subjected tothe following evaluation tests.

Evaluation of Samples

The samples were evaluated in the same manner as in evaluations 1 to 3in A-3 above.

The results were as shown in Table 3 below.

TABLE 3 Water-based Eval- Eval- Eval- Primer pigment ink uation uationuation liquid composition 1 2 3 Example C1 Primer Black ink A A A liquid1e Example C2 Primer Black ink A A A liquid 2e Example C3 Primer Cyanink A A A liquid 1e Example C4 Primer Magenta ink A A A liquid 1eExample C5 Primer Yellow ink A A A liquid 1e Example C6 None Black ink CB C (comparative) Example C7 None Cyan ink A B B (comparative) ExampleC8 None Magenta ink B B C (comparative) Example C9 None Yellow ink B C C(comparative)

D. Primer Liquid (Cyclic Amide Compound)

D-1. Preparation of Primer Liquids

Primer liquids according to the present invention were preparedaccording to the following formulations.

Primer Liquid 1a:

2-Pyrrolidone 10.0% by weight  ε-Caprolactam 10.0% by weight Styrene-acrylic acid copolymer 5.0% by weight (solid basis) Diethyleneglycol 4.0% by weight Diethylene glycol monobutyl ether 3.0% by weightSurfynol 465 1.0% by weight Pure water Balance

Primer Liquid 2a:

N-Methyl-2-pyrrolidone 10.0% by weight  ε-Caprolactam 10.0% by weight Styrene-acrylic acid copolymer 5.0% by weight (solid basis) Diethyleneglycol 4.0% by weight Diethylene glycol monobutyl ether 3.0% by weightSurfynol 465 1.0% by weight Pure water Balance

D-2. Preparation of Water-Based Pigment Ink Compositions

Water-based pigment ink compositions were prepared according to theformulations as described in A-2.

D-3. Evaluation Test

Preparation of Printing Samples Examples D1 to D5

Treatment liquid 1a or treatment liquid 2a was coated at 50% duty onto anon-surface-treated specialty flexible vinyl chloride film (ScotchcalFilm, manufactured by Sumitomo 3M Ltd.) for ink jet printing, with anink jet printer (TM-J8000; manufactured by Seiko Epson Corporation).Thereafter, the coated film was dried in a thermostatic chamber kept ata temperature of 60° C. and a relative humidity of 20% for one hr toform a primer film. Immediately after that, a 100% duty pattern wasprinted with an ink jet printer (TM-J8000; manufactured by Seiko EpsonCorporation) loaded with a black ink or with a cyan ink, a magenta ink,and a yellow ink.

Printing samples were dried in a thermostatic chamber kept at atemperature of 60° C. and a relative humidity of 20% for one hr andfurther at room temperature for one day and were then subjected to thefollowing evaluation tests.

Preparation of Printing Samples Examples D6 to D9 (Comparative Examples)

Printing samples of Examples D6 to D9 were prepared in the same manneras in Examples C6 to C9. The printing samples were dried in athermostatic chamber kept at a temperature of 60° C. and a relativehumidity of 20% for one hr and further at room temperature for one dayand were then subjected to the following evaluation tests.

Evaluation of Samples

The samples were evaluated in the same manner as in evaluations 1 to 3in A-3 above.

The results were as shown in Table 4 below.

TABLE 4 Water-based Eval- Eval- Eval- Primer pigment ink uation uationuation liquid composition 1 2 3 Example D1 Primer Black ink A A A liquid1a Example D2 Primer Black ink A A A liquid 2a Example D3 Primer Cyanink A A A liquid 1a Example D4 Primer Magenta ink A A A liquid 1aExample D5 Primer Yellow ink A A A liquid 1a Example D6 None Black ink CB C (comparative) Example D7 None Cyan ink A B B (comparative) ExampleD8 None Magenta ink B B C (comparative) Example D9 None Yellow ink B C C(comparative)

E. Ink Composition Liquid (Cyclic Ester Compound)

E-1. Preparation of Ink Compositions

Ink compositions 1e to 7e were prepared according to the followingformulations.

Ink Composition 1e

γ-Butyrolactone 2.0% by weight Tetrahydrofuran 3.0% by weight C.I.Pigment Yellow 2.0% by weight Styrene-acrylic acid copolymer 1.0% byweight (thermoplastic resin) (solid basis) Diethylene glycol 4.0% byweight Diethylene glycol monobutyl ether 3.0% by weight Surfynol 4651.0% by weight Pure water Balance

Ink Composition 2e

γ-Butyrolactone 2.0% by weight 1,4-Dioxane 3.0% by weight C.I. PigmentYellow 2.0% by weight Styrene-acrylic acid copolymer 1.0% by weight(thermoplastic resin) (solid basis) Diethylene glycol 4.0% by weightDiethylene glycol monobutyl ether 3.0% by weight Surfynol 465 1.0% byweight Pure water Balance

Ink Composition 3e

Propylene carbonate 2.0% by weight Tetrahydrofuran 3.0% by weight C.I.Pigment Yellow 74 2.0% by weight Styrene-acrylic acid copolymer 1.0% byweight (thermoplastic resin) (solid basis) Diethylene glycol 4.0% byweight Diethylene glycol monobutyl ether 3.0% by weight Surfynol 4651.0% by weight Pure water Balance

Ink Composition 4e

Propylene carbonate 2.0% by weight 1,4-Dioxane 3.0% by weight C.I.Pigment Yellow 74 2.0% by weight Styrene-acrylic acid copolymer 1.0% byweight (thermoplastic resin) (solid basis) Diethylene glycol 4.0% byweight Diethylene glycol monobutyl ether 3.0% by weight Surfynol 4651.0% by weight Pure water Balance

Ink Composition 5e (Comparative Example)

γ-Butyrolactone 2.0% by weight C.I. Pigment Yellow 74 2.0% by weightStyrene-acrylic acid copolymer 1.0% by weight (thermoplastic resin)(solid basis) Diethylene glycol 4.0% by weight Diethylene glycolmonobutyl ether 3.0% by weight Surfynol 465 1.0% by weight Pure waterBalance

Ink Composition 6e (Comparative Example)

Tetrahydrofuran 3.0% by weight C.I. Pigment Yellow 74 2.0% by weightStyrene-acrylic acid copolymer 1.0% by weight (thermoplastic resin)(solid basis) Diethylene glycol 4.0% by weight Diethylene glycolmonobutyl ether 3.0% by weight Surfynol 465 1.0% by weight Pure waterBalance

Ink Composition 7e (Comparative Example)

C.I. Pigment Yellow 74 2.0% by weight Styrene-acrylic acid copolymer1.0% by weight (thermoplastic resin) (solid basis) Diethylene glycol4.0% by weight Diethylene glycol monobutyl ether 3.0% by weight Surfynol465 1.0% by weight Pure water Balance

E-3. Evaluation Test

Preparation of Printing Samples:

Printing samples were prepared using the ink compositions prepared inthe above Examples and Comparative Examples. Specifically, printing wasperformed at 100% duty on a non-surface-treated specialty flexible vinylchloride film (Scotchcal Film, manufactured by Sumitomo 3M Ltd.) for inkjet recording with an ink jet printer (TM-J8000; manufactured by SeikoEpson Corporation) loaded with an ink composition. The printing samplesthus obtained were dried at a temperature of 60° C. and a relativehumidity 20% in a thermostatic chamber for one hr and further at roomtemperature for one day and were then subjected to the followingevaluation tests.

Evaluation of Samples:

Evaluation a: Adhesion

A pressure-sensitive adhesive tape (Cello-Tape No. 252; manufactured bySekisui Chemical Co., Ltd.) was applied to the printing sample in itsprinted part and was rubbed twice or thrice with a finger. Thereafter,the pressure-sensitive adhesive tape was separated from the printingsample. The rubbed printed part was visually inspected. The results wereevaluated according to the following criteria.

A: No separation of the ink (colorant) from the vinyl chloride film.

B: Partial separation of the ink (colorant) from the vinyl chloridefilm.

C: Complete separation of the ink (colorant) from the vinyl chloridefilm.

Evaluation b: Waterfastness

One drop of tap water was deposited on the printing sample in itsprinted part, and the sample was allowed to stand for one min. The waterdroplet was wiped off with gauze. After the wiping-off of the waterdroplet, the state of the printed part and the state of the gauze werevisually inspected. The results were evaluated according to thefollowing criteria.

A: The ink (colorant) was not separated from the vinyl chloride film atall, and no coloration of the gauze was observed.

B: A part of the ink (colorant) was separated from the vinyl chloridefilm, and coloration of the gauze was observed.

C: The ink (colorant) was completely separated from the vinyl chloridefilm, and coloration of the gauze was observed.

The results were as shown in Table 5 below.

TABLE 5 Eval- Eval- Ink com- Cyclic ester Cyclic ether uation uationposition compound compound 1 2 1e γ-Butyrolactone Tetrahydrofuran A A 2eγ-Butyrolactone 1,4-Dioxane A A 3e Propylene Tetrahydrofuran A Acarbonate 4e Propylene 1,4-Dioxane A A carbonate 5e γ-Butyrolactone NoneB B (Comparative Example) 6e None Tetrahydrofuran B B (ComparativeExample) 7e None None C C (Comparative Example)

F. Ink Composition Liquid (Cyclic Amide Compound)

F-1. Preparation of Ink Compositions

Ink compositions 1a to 7a were prepared according to the followingformulations.

Ink Composition 1a

2-Pyrrolidone 5.0% by weight ε-Caprolactam 5.0% by weightTetrahydrofuran 3.0% by weight C.I. Pigment Yellow 74 2.0% by weightStyrene-acrylic acid copolymer 1.0% by weight (thermoplastic resin)(solid basis) Diethylene glycol 4.0% by weight Diethylene glycolmonobutyl ether 3.0% by weight Surfynol 465 1.0% by weight Pure waterBalance

Ink Composition 2a

2-Pyrrolidone 5.0% by weight ε-Caprolactam 5.0% by weight 1,4-Dioxane3.0% by weight C.I. Pigment Yellow 74 2.0% by weight Styrene-acrylicacid copolymer 1.0% by weight (thermoplastic resin) (solid basis)Diethylene glycol 4.0% by weight Diethylene glycol monobutyl ether 3.0%by weight Surfynol 465 1.0% by weight Pure water Balance

Ink Composition 3a

N-Methyl-2-pyrrolidone 5.0% by weight ε-Caprolactam 5.0% by weightTetrahydrofuran 3.0% by weight C.I. Pigment Yellow 74 2.0% by weightStyrene-acrylic acid copolymer 1.0% by weight (thermoplastic resin)(solid basis) Diethylene glycol 4.0% by weight Diethylene glycolmonobutyl ether 3.0% by weight Surfynol 465 1.0% by weight Pure waterBalance

Ink Composition 4a

N-Methyl-2-pyrrolidone 5.0% by weight ε-Caprolactam 5.0% by weight1,4-Dioxane 3.0% by weight C.I. Pigment Yellow 74 2.0% by weightStyrene-acrylic acid copolymer 1.0% by weight (thermoplastic resin)(solid basis) Diethylene glycol 4.0% by weight Diethylene glycolmonobutyl ether 3.0% by weight Surfynol 465 1.0% by weight Pure waterBalance

Ink Composition 5a (Comparative Example)

2-Pyrrolidone 5.0% by weight ε-Caprolactam 5.0% by weight C.I. PigmentYellow 74 2.0% by weight Styrene-acrylic acid copolymer 1.0% by weight(thermoplastic resin) (solid basis) Diethylene glycol 4.0% by weightDiethylene glycol monobutyl ether 3.0% by weight Surfynol 465 1.0% byweight Pure water Balance

Ink Composition 6a (Comparative Example)

Tetrahydrofuran 3.0% by weight C.I. Pigment Yellow 74 2.0% by weightStyrene-acrylic acid copolymer 1.0% by weight (thermoplastic resin)(solid basis) Diethylene glycol 4.0% by weight Diethylene glycolmonobutyl ether 3.0% by weight Surfynol 465 1.0% by weight Pure waterBalance

Ink Composition 7a (Comparative Example)

C.I. Pigment Yellow 74 2.0% by weight Styrene-acrylic acid copolymer1.0% by weight (thermoplastic resin) (solid basis) Diethylene glycol4.0% by weight Diethylene glycol monobutyl ether 3.0% by weight Surfynol465 1.0% by weight Pure water Balance

F-3. Evaluation Test

In the same manner as in E-3, printing samples were prepared and wereevaluated.

The results were as shown in Table 6 below.

TABLE 6 Eval- Eval- Ink com- Cyclic amide Cyclic ether uation uationposition compound compound 1 2 1a 2-Pyrrolidone Tetrahydrofuran A Aε-Caprolactam 2a 2-Pyrrolidone 1,4-Dioxane A A ε-Caprolactam 3aN-Methyl-2- Tetrahydrofuran A A pyrrolidone ε-Caprolactam 4a N-Methyl-2-1,4-Dioxane A A pyrrolidone ε-Caprolactam 5a 2-Pyrrolidone None A A(Comparative ε-Caprolactam Example) 6a None Tetrahydrofuran B B(Comparative Example) 7a None None C C (Comparative Example)

1. An ink-jet ink composition for formulation of an image having a recording face formed of a plastic film, wherein said ink composition comprises at least a cyclic ester compound of formula (1), a thermoplastic resin, a colorant, and a main solvent, said thermoplastic resin being dispersed in said ink composition: wherein

R¹ represents a straight chain or branched chain C2 to C12 saturated hydrocarbon chain, and X¹ represents —CH₂— or —O—.
 2. The ink-jet ink composition according to claim 1, wherein in formula (1), R¹ represents a straight chain or branched chain C2 to C5 saturated hydrocarbon group.
 3. The ink jet ink composition according to claim 1, wherein said cyclic ester compound is selected from the group consisting of γ-butyrolactone, ε-caprolactone, propylene carbonate, and ethylene carbonate.
 4. The ink-jet ink composition according to claim 1, which further comprises a surfactant and wherein said surfactant is an acetylene glycol surfactant.
 5. The ink-jet ink composition according to claim 1, which further comprises an organic solvent having low surface tension, and wherein said organic solvent having low surface tension is diethylene glycol monobutyl ether or triethylene glycol monobutyl ether.
 6. A method for formulation of an image by ink jet recording, comprising ejecting and depositing droplets of an ink composition according to claim 1 onto a recording medium having a recording face of a plastic film to perform printing.
 7. The method according claim 6, which further comprises a heating step of heating the ink composition deposited onto the recording face to form a resin film.
 8. The method according to claim 6, wherein the recording face is polyvinyl chloride film.
 9. A recorded matter printed by a method according to claim
 6. 